Britain has voted to leave the European Union, forcing the resignation of Prime Minister David Cameron and dealing the biggest blow to the European project of greater unity since World War II.

Global financial markets plunged as results from Thursday's referendum showed a near 52-48 percent split for leaving.

The pound fell more than 10 percent against the dollar to levels last seen in 1985, its biggest one-day fall in history, on fears the decision could hit investment in the world's fifth-largest economy, threaten London's role as a global financial capital and usher in months of political uncertainty.