Britain's Prime Minister David Cameron has slammed any moves to forge a United States of Europe.

Cameron, who has shaken up Europe's political landscape by offering to let citizens vote on whether to leave the 27-nation European Union, says forcing countries into a single entity would be a "great mistake."

Speaking Thursday at the World Economic Forum in the Swiss resort of Davos, Cameron says Britain would stand against any moves to shoehorn countries into a centralized political union.

Many politicians, particularly those in the 17 countries that use the euro, think closer political ties are needed. Some even think something resembling the United States should be Europe's end-game.

A number of European leaders have accused Cameron of putting the bloc at risk to deal with domestic political problems.