Britain should stage an in/out referendum on membership of the European Union (EU) once the current crisis in the economy is over and the future shape of the eurozone has become clear, a member of Ed Miliband's shadow cabinet has said.
Shadow defence secretary Jim Murphy said that "almost everyone" in the Labour Party will campaign for Britain to stay in the EU if a poll is called.
His comments will fuel speculation that Mr Miliband is considering offering a referendum in the hope of exposing Conservative divisions on the issue and ending years of argument over the UK's relations with Europe.
The Labour leader's close ally Jon Cruddas said last week that the policy review he is chairing will look at the case for an in/out referendum. But he was slapped down by former party leader Lord Kinnock, who described a public vote on Europe as "a gigantic distraction (which) would disable political and economic activity in the rest of the EU".
Speaking to BBC2's Daily Politics show from Labour's Manchester conference, Mr Murphy said: "I think at some point, there will have to be a referendum on the EU ... I don't think it's for today or for the next year, but I think it should happen."
The EU will look very different once the 17 countries which use the single currency have agreed on fiscal and political arrangements for the eurozone, said Mr Murphy. "I think after that, the time for the referendum will be upon us," he said. "I don't have a calendar with a date circled. I think we will do it when the time is right."
Mr Murphy said he would not back a "pick and mix" poll offering voters a range of different options for the UK's future relationship with the EU.
The question for any referendum should be designed by the independent Electoral Commission, he said. But he added: "My preference would be an in-or-out referendum when the time comes."
He added: "Whenever the referendum comes, almost everyone in the Labour Party, along with the Liberal Democrats and British business, will be arguing we should stay part of the EU, because it is good for our economy and good for Britain."
Prime Minister David Cameron hinted last week that he might be ready to call an EU referendum after the 2015 general election, saying that the coming years would see "opportunities for a new settlement between Britain and Europe" which would require "fresh consent from the British people".