Britain votes in historic referendum on EU

London : Millions of Britons began voting Thursday in a bitterly-fought, knife-edge referendum that could tear up the island nation's EU membership and spark the greatest emergency of the bloc's 60-year history.

A record 46.5 million voters have registered to decide Britain's future in the 28-nation European Union, which was born out of a determination to unite in lasting peace after the carnage of two world wars.

Across much of southeast England, many voters braved torrential rain to have their say in a battle fought on two main fronts: immigration and the economy.

Experts have predicted a high turnout.

The once-in-a-generation referendum asks: "Should the United Kingdom remain a member of the European Union or leave the European Union?"

In one of the last opinion polls before the vote, "Remain" took a lead with 48 percent against "Leave" on 42 percent. The rest were undecided, according to the telephone survey by ComRes for the Daily Mail and ITV News.

Two other polls published on the eve of the referendum -- both conducted over the Internet -- had put the "Leave" camp ahead by one or two percentage points, well within the margin of error.

"Leave" advocates say a Britain cut loose the EU will be able to rein in high levels of immigration and take back power from Brussels, while the "Remain" camp warns of a huge economic shock if Britain abandons the bloc.