David Ramos/Getty Images

Catalonia leader Artur Mas signed a decree calling for an independence vote on Saturday, directly defying Spain's central government in Madrid.

"Catalonia wants to decide pacifically and democratically its political future," Mas said. "Nobody should fear that somebody expresses his opinion by placing a vote in a ballot box."

Catalonia includes Barcelona, and it is one of Spain's most prosperous regions, accounting for one-fifth of the country's economy. While the region has always been independence-minded, Spain's fiscal woes have spurred increased support for Catalonia's secessionist movement. Supporters of the independence vote say Madrid disproportionately uses Catalan taxes in order to support the country's poorer regions. Catalonian lawmakers reflected those frustrations in a 106-28 vote in favor of authorizing the referendum.

The call for a vote comes in the wake of Scotland's independence referendum earlier this month. Voters chose to remain part of the United Kingdom, but Mas says the exercise was "a great lesson in democracy."

Spain's prime minister, Mariano Rajoy, swiftly panned the referendum in a statement made by his deputy prime minister, saying any vote held would be "unconstitutional."