LONDON (AFP) - Britain's centre-left opposition Labour party will support Prime Minister David Cameron's proposal for a referendum on European Union membership but will make the case to stay, party leaders told the Sunday Times.

"The British people want to have a say on the UK's membership of the European Union," the party's acting leader Harriet Harman and foreign affairs spokesman Hilary Benn were quoted by the paper as saying.

"Labour will therefore now support the EU referendum bill," they said, adding that they wanted "reform in Europe - on benefits and the way the EU works".

"The Labour party doesn't want to see the UK stumble inadvertently towards EU exit. We will make the case for our continued membership," they said.

Cameron has called for a referendum to be held by 2017 and the plan is due to be unveiled on Wednesday when Queen Elizabeth II delivers a speech in parliament outlining the new government's legislative programme.

The prime minister has said he will support continued membership as long as he can negotiate a series of reforms, including limiting access to Britain's welfare system for migrants from other EU countries.

The British leader is starting out on a new five-year term after a general election earlier this month that handed his centre-right Conservative Party a majority.

During the election campaign, Labour had opposed the holding of a referendum on EU membership, warning of the economic uncertainty that it could generate.