Labour makes no sense on Europe, says David Cameron
David Cameron has accused Labour of making "no sense whatsoever" on Europe, after leader Ed Miliband said it was "unlikely" his party would hold a referendum on staying in the EU.
Mr Cameron said only the Conservatives, who have promised an in/out referendum by the end of 2017, were being "clear".
But Mr Miliband accused the Tories of having an "obsession" with Europe.
The argument between the two leaders comes as they prepare for the European Parliament elections in May.
The recent rise in the opinion polls of the UK Independence Party - which wants the UK to withdraw from the EU - has increased the focus on the issue.
Mr Cameron, some of whose backbench MPs also want to quit the 28-nation group, has promised the in/out referendum if his party wins a majority at the 2015 general election.
'Policy by committee'
This should take place after a full renegotiation of powers with Brussels, he argues.
Earlier Mr Miliband said there was an "overwhelming economic case" for EU membership.
He promised to introduce a "lock", so if the UK was asked to transfer powers to the EU, there would be an in/out referendum.
But he added: "I believe it is unlikely this lock will be used in the next parliament."
He also criticised the prime minister for creating an "arbitrary timetable", ensuring a "Conservative government would be dominated by an all-consuming and damaging obsession within his party about whether Britain should leave the EU".
But Mr Cameron, who is visiting Israel, attacked his rival's position.
"It is not a proposal for an in/out referendum," the prime minister said.
"It is a policy clearly designed by a committee who obviously couldn't agree what to do and have come up with a policy that makes no sense whatsoever."
He added: "The British people now have a very, very clear choice. At the next election they can elect a Conservative government that will renegotiate Britain's position in Europe and give people a guaranteed in-out referendum by the end of 2017.
"If they get a Labour government, they will get no referendum, no choice, no reform, nothing. It couldn't be clearer."
The coalition has already enshrined in law a "referendum lock", promising a vote on whether to transfer further powers to Brussels if the situation arises - but not on whether to leave the EU.
Conservative attempts to legislate for an in/out referendum in 2017 have been thwarted by the Liberal Democrats.
Lib Dem Energy Secretary Ed Davey said the Tories had "changed position under pressure from their backbenchers and UKIP".
Meanwhile UKIP leader Nigel Farage said Mr Miliband had put "himself squarely on the side of the Westminster elite and against the British public".