Scotland's top politician warned Tuesday that a future United Kingdom referendum on leaving the European Union could spark a new drive for independence in pro-EU Scotland.

First Minister Nicola Sturgeon is calling for a "double-majority" voting system in the referendum planned for 2017 that would require support from the citizens of England, Wales, Northern Ireland and Scotland before the United Kingdom as a whole could leave the EU.

Sturgeon warned in a speech in Brussels that British Prime Minister David Cameron's "in-out" referendum to be decided by a simple majority of people living in the U.K. "would provoke a strong backlash."

"The groundswell of anger among many ordinary people in Scotland in these circumstances could produce a clamor for another independence referendum that may well be unstoppable," she told EU experts, politicians and media representatives.

Scots voted against independence from Britain in a referendum last September by 55.3 percent to 44.7 percent.

"If we have that double majority provision, then Scotland can't be taken out of the European Union against its will, nor could Wales or Northern Ireland," Sturgeon said, in a speech that came almost 40 years to the day after a referendum in Britain on whether to stay in what was then the European Economic Community.

Ahead of the referendum, Cameron has been canvassing leaders of other EU nations to see what kind of concessions he can win to keep Britain in.

Some share a few of his concerns but there is little appetite for any change that would involve long and divisive amendments to the EU's treaties.

Sturgeon said Cameron was leading voters on a "dangerous path" because EU partners will not "put their own interests out the window" to keep Britain in.