A bill allowing a referendum on Britain's membership of the EU has only a 50/50 chance of making it through the House of Commons, the MP promoting it has said.

Stockton South MP James Wharton is putting forward legislation drafted by the Conservative Party leadership, which would require a national referendum by the end of 2017.

Prime Minister David Cameron has pledged to do everything possible to bring the EU referendum bill to a vote, but Wharton conceded the Bill's prospects appeared to be a " very close-run thing".