LONDON (AFP) - London Mayor Boris Johnson indicated Wednesday that he would stand for election to the House of Commons next year, a move that could eventually position him as a successor to British Prime Minister David Cameron.

The comments from Mr Johnson, known for his messy shock of blond hair and clownish antics, end months of speculation about whether he would return to national politics.

Some in Mr Cameron's Conservative Party see Mr Johnson as a popular figure with a high profile who could be a successful future leader if he were to win a seat at next May's general election.

"In all probability I will try to find somewhere to stand in 2015," Johnson said following a speech in London.

But the 50-year-old added that he intended to serve out his full term as London's mayor, which does not end until 2016.

He has always publicly played down his chances of eventually becoming prime minister, saying they were about as good as those "of finding Elvis on Mars or my being reincarnated as an olive."

Mr Cameron's Conservatives, currently senior partners in a coalition government, face a tough fight to win next year's election.

A YouGov/Sun poll out Wednesday put the Conservatives on 33 per cent, the main opposition Labour on 38 per cent, junior coalition partners the Liberal Democrats on eight percent and the anti-EU UK Independence Party on 12 per cent.

While Mr Johnson has a high international profile, several other leading Conservatives are also seen as strong contenders to succeed Cameron should he step down.

These include finance minister George Osborne and Home Secretary Theresa May.

Mr Johnson and Mr Cameron are old rivals who attended the elite Eton College and Oxford University together.

Despite their long rivalry, Mr Cameron welcomed the announcement as "great news", writing on Twitter: "I've always said I want my star players on the pitch." Leading political commentator Matthew d'Ancona said last week Johnson's reputation was such that the Conservative party would "brood unhealthily" if he did not stand in the next leadership election.

"Whoever succeeds Cameron as Conservative leader must be Boris, or someone who has defeated Boris," he wrote in the London Evening Standard.

Mr Johnson was previously a lawmaker in the House of Commons between 2001 and 2008. At that point, his progress was hampered by blunders including suggesting that the people of Liverpool in northwest England were wallowing in "disproportionate" grief for a local man kidnapped and executed in Iraq.

He was forced to go to the city to apologise in person.

Mr Johnson stood down as a member of parliament when he won the London mayoral election in 2008. As mayor, his most high-profile success was running the city during the 2012 Olympics.

He provided one of the most iconic images of the Games when he was left dangling mid-air after being stuck on a zip wire waving two British flags in front of a watching crowd.

In recent days, Johnson has been setting out his stall on global issues including Israeli operations in Gaza, which he called "utterly horrifying and unacceptable".

Mr Johnson's speech on Wednesday also addressed Britain's role in the European Union ahead of an in-out referendum on membership to be held in 2017 if the Conservatives win the election.

He said Brussels was afflicted by "sclerosis" and that a British exit from the EU could be a "win-win" if London was unable to secure reforms which it believes are necessary.