At least 145 people are now believed to have been killed in India after a train derailed near the village of Pukhrayan, in Uttar Pradesh, in the early hours of Sunday.
The cause of the crash is not yet known, but the Times of India quoted sources as saying a fracture in the track could have been to blame.
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Railway minister Suresh Prabhu, who said he was "personally monitoring the situation closely", warned the "strictest possible action will be taken against those who could be responsible for the accident". He also promised to launch an immediate investigation and begin the process of compensating those injured.
Around 23 million passengers a day use the country's vast train network, the fourth largest in the world. Accidents remain "fairly common in India, where much of the railway equipment is out of date", says the BBC. This was one of the worst, if not the worst, this century.
Last year, India announced an investment of $137bn (£111bn) over five years to modernise and expand the railways.