Prime Minister David Cameron lost a parliamentary vote on the long-term European Union budget on Wednesday after members of his Conservative Party rebelled, dealing a damaging blow to the government.

In a defeat that could undermine Cameron's authority, dozens of Conservative members of parliament defied him to support a call for Britain to demand a real terms cut in the EU budget from 2014 to 2021.

The vote - carried by 13 votes - has no legal weight, but the defeat is likely to raise questions over Cameron's control of the coalition government and his ability to reign in the Conservatives' anti-European arm.

(Reporting by Peter Griffiths Editing by Maria Golovnina)