The plan will "reduce energy costs by about £100 a year for an average family by capping gas and electricity bills for households paying standard variable tariffs," says The Times.
A price cap is precisely what many critics of the sector have been demanding - and it comes after five of the big six have hiked prices in recent months.
But the pledge has sparked a wave of criticism - from within the sector, of course, but also from political opponents who have accused the Tories of "hypocrisy".
When Ed Miliband, then Labour leader, announced a two-year energy price freeze ahead of the 2015 election the Conservatives branded the policy "shocking" and there were warnings of a hit to jobs and investment, says The Independent.
Tory Defence Secretary Sir Michael Fallon said in a BBC radio interview: "You’ll find when the manifesto is published in a couple of weeks we are not proposing a freeze.
"A freeze is very different to a cap.”
“We didn’t introduce a freeze because a freeze would have stopped you taking advantage of prices when they dropped.”
But Miliband hit back, writing on Twitter: "Fallon, of course, talking garbage ... 2015 manifesto: Labour will freeze energy bills until 2017, ensuring that bills can fall but not rise.”
Iain Conn, boss of British Gas owner Centrica, told the Daily Telegraph: "We do not believe price regulation is in consumers’ interests. Price regulation will result in reduced competition and choice, stifle innovation and potentially impact customer service.”
Julian Jessop, chief economist at the Institute of Economic Affairs, said the move was "clumsy and counterproductive" and that it was better to find ways to get more customers to switch.
Tory manifesto could include Miliband-like energy price pledge
19 April
An energy price cap of the sort proposed by the Ed Miliband before the last election might feature in the Tory manifesto, say reports.
Earlier this week, The Guardian reported a government "crackdown" on energy companies was expected "as soon as next Monday".
It added this would "most likely [be] in the form of a price cap on the standard variable tariffs affecting nearly two-thirds of households".
However, now Theresa May has called for a general election, backed by a majority of MPs this afternoon, this could be in doubt.
The government is still able to make the announcement ahead of the dissolution of parliament, which the Guardian says will be 3 May.
If it fails to do so, a potential cap could be included as a manifesto pledge for what a re-elected Tory government would seek to achieve – a move some Conservative strategists may prefer.
Speaking earlier today, Business Secretary Greg Clark said: "We will have to reflect on timing."
He added, however, that the election call would not mean a "delay" in eventual implementation and that the crackdown would be "muscular and strong".
Energy charges are already being capped for pre-paid customers and Ofgem, the energy regulator, is bringing forward measures to encourage standard tariff customers to switch providers, but critics have long argued the government could do more.
Five of the "big six" energy suppliers – EDF, E.ON, Npower, SSE and Scottishpower – have increased their prices recently, blaming rising wholesale costs and other factors.
However, Ofgem has said that EDF's latest rise - its second in four months – is "difficult to justify".
EDF's second price hike in four months is 'difficult to justify'
12 April
Government hints it will step in after energy supplier adds £78 to average customer's bills
One of the 'Big Six' energy suppliers has announced a second price rise in four months, prompting further calls for government intervention in the energy market.
EDF says its standard tariff electricity prices will increase by nine per cent and its gas prices by 5.5 per cent on 1 June. This will add £78 to the average annual bill which will rise to £1,160.
On 1 March, EDF's electricity prices rose by 8.4 per cent, although its gas prices were cut by 5.2 per cent in January.
The BBC says taking both rises together means the 1.8 million electricity customers on standard variable tariffs will pay a total of 18.1 per cent more – but gas prices are effectively unchanged.
Around 1.8 million EDF customers are unaffected at present as they are on cheaper, fixed-rate deals.
Dermot Nolan, chief executive of the energy regulator Ofgem, says EDF's second increase in four months has come despite the absence of a "dramatic rise" in wholesale prices. It's therefore "difficult to justify," he says.
He adds that the move provides "further evidence that the energy market is not working in all consumers' interests".
Ofgem is already acting to cap charges for pre-paid energy customers and is working on plans to intervene in the market to encourage customers on expensive standard tariffs to switch to cheaper deals.
It also appears likely the government will get more involved in the market.
A government spokesman told The Guardian: "It's another sign the market isn't working, and we will shortly set out proposals to help energy consumers as part of the government's Plan for Britain."
EDF's move follows price hikes this year by Npower, Eon and Scottish Power. British Gas has frozen its prices until August.
Companies generally cite cost increases beyond wholesale gas and electricity price rises, including the cost of government green energy schemes and smart meter roll-out programmes.
"I know that price rises are never welcome, but the industry is facing significant cost increases," says EDF's chief executive, Vincent de Rivaz.
"To be a sustainable and responsible business, we aim to make a fair margin in supplying customers. This fair margin allows us to invest for the long term, in particular in good service, innovation and smart metering."
SSE latest of 'big six' to increase energy prices
13 March
Customers will pay almost 15 per cent more for electricity from end of April, company announces
In a move that will hit millions of households, yet another of the so-called "big six" energy providers that dominate the UK market has announced it is increasing prices.
SSE has announced a massive 14.9 per cent increase in its electricity prices from 28 April. While it will keep gas prices unchanged, duel-fuel customers will pay around 6.9 per cent, or £73, more per year.
In all, four of the largest six companies in the market have now confirmed price rises, says the BBC:
EDF Energy increased electricity prices by 8.4 per cent from 1 March, although it did cut its gas prices by 5.2 per cent in January;
Npower is raising its standard tariff electricity prices by 15 per cent from 16 March and gas prices by 4.8 per cent;
Scottish Power's standard electricity prices will increase by an average of 10.8 per cent and gas by 4.7 per cent on 31 March, and
E.On is increasing electricity prices by an average of 13.8 per cent and gas prices by 3.8 per cent, on 26 April.
Only British Gas has bucked the trend, announcing it is freezing prices until August and rolling out a series of rewards for customers, including discounted Sky TV packages.
SSE's price rise will affect its standard variable rate, which currently affects 85 per cent of its customers, or 2.8 million people. Nationwide, as many as 20 million people are on such standard tariffs, mostly with the Big Six companies.
The regulator is intervening to freeze prices for pre-payment customers and is exploring ways to encourage most customers to shop around for cheaper fixed-rate deals.
What is happening to your energy bills?
13 March 2017
Companies are offering incentives - but they pale in comparison to the real benefits of shopping around.
Energy bills have been firmly in the headlines this week with news of loyalty programmes, prepay caps and price hikes. Here’s what you need to know.
Rewards for loyal customers
Two of the Big Six energy firms are considering bringing in rewards for loyal customers. Npower and EDF told a panel of MPs they were looking into what perks they could offer to customers who stay with them for long periods.
“For example, could we provide our standard customers with a free boiler service? We’ve done a trial of that, to see whether it resonated with customers,” Simon Stacy, the managing director of domestic markets for Npower, told the Business and Energy Committee.
“We want to try and reward customers in a way they wouldn’t expect.”
Is that good news?
No, not really. The loyalty schemes are likely to be offered to customers who have been sat on a company’s standard tariff for several years. Those tariffs are the most expensive, switching to a better tariff would typically save the average household around £200 a year. A free boiler service is worth around £60.
So, if your energy firm offers you a loyalty reward take it as a clear sign you should check your deal and shop around to save yourself a lot of money.
A cap on prepay charges
The energy regulator, Ofgem, has announced that a new cap on prepay meter charges. The level of the cap will vary depending on where you live, the type of meter you have and whether you are pre-paying for electricity or gas but it is expected to save the average pre-pay meter user around £80 a year.
“Customers who prepay for their energy are denied the best deals on the market available to those using other payment methods,” says Ofgem chief executive Dermot Nolan.
“They are also more likely to be in vulnerable circumstances, including fuel poverty. The temporary cap will protect these households as we work to deliver a more competitive, fairer and smarter market for all consumers.”
The price cap will be reviewed every six months and is expected to stay until 2020.
Good news?
Yes, but Ofgem could have done a little better, is the response from consumer groups. Research has found that households on pre-pay meters typically pay £220 more a year for their energy than those on the cheapest deals.
“This cap should stop some of the poorest households paying over the odds to heat and light their homes,” says Gillian Guy, chief executive of Citizens Advice.
“It will help millions save money but action shouldn’t stop there. The government has rightly expressed concern that loyal customers on standard tariffs are paying over the odds for their gas and electricity.
"It could help more struggling households, including low-income pensioners and families by extending this cap to people eligible to receive the Warm Homes Discount.”
Energy bills rise by 10%
In amongst all the government and regulatory efforts to bring energy bills under control, one company has announced a big hike in prices.
In what can be seen as a slap in the face for Ofgem Npower chose this week to announce its biggest price rises since 2013: Over one million Npower customers will see their standard tariffs rise by 10.4 per cent in March, increasing the average household bill by more than £100 a year.
The rest of the Big Six are expected to follow suit with similar price hikes - and Scottish Power announced an increase of close to eight per cent on Friday.
The move has been met by anger in Parliament with Business Secretary Greg Clark saying, “loyal customers are being taken for granted by the big energy firms.”
A spokesman for the Prime Minister stated that the government was prepared to act to protect consumers if price rises were seen as unfair.
“We are concerned by Npower’s planned increases – we are committed to getting the best for households. Suppliers are protected from recent fluctuation in wholesale energy prices which are set two years in advance so we expect them to treat customers fairly and clearly where markets are not working we are prepared to act.”
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