The French president held a news conference with the Prime Minister at Downing Street but refused to comment on "ridiculous rumours" about his private life.

He said he shared Mr Brown's views on Iran, nuclear power and global financial reform and described him as a "convinced and convincing reformer".

Mr Sarkozy added: "The place of our British friends is bang in the middle of Europe."

But it would be inappropriate to comment on the impending General Election, he added.

The French leader also met Conservative leader David Cameron in a separate meeting.

With Mr Cameron leading in the opinion polls, the French president would have wanted to gauge his views on a range of European issues.

Last year, the Conservatives withdrew from the European People's Party, the large centre-right group in the European Parliament that includes France and Germany, a move at which Mr Sarkozy expressed "regret".

The party formed a new alliance with members from Poland and the Czech Republic because it feared a "slide into a federal Europe".

Senior Tory Edward McMillan-Scott, once leader of the Conservative MEP faction in the European Parliament, has blamed the move for his defection to the Liberal Democrats.

He was expelled from the Tories six months ago after defying the party by challenging Polish MEP Michal Kaminski for a key role as one of the European Parliament's Vice-Presidents.

Mr McMillan-Scott won, infuriating Mr Cameron and forcing the Tories to appease Mr Kaminski by offering him chairmanship of the new "European Conservatives and Reformists" group in Strasbourg.

The Tory whip was removed from Mr McMillan-Scott, who subsequently lost an appeal against his treatment.

"My reasons for joining the Liberal Democrats are that in Nick Clegg they have a leader whom I like, admire and respect. They are internationalists, not nationalists," he said.

The French president travelled to London without his wife, as the world's media fizzed with rumours about the first couple.

Mr Sarkozy was clearly irritated by questions at a press conference in Downing Street about internet rumours that both he and model-turned-singer Carla Bruni were having affairs.

"You clearly have no understanding of a president's timetable - I don't have a second to waste in these rantings, not even half a second," he told the French reporter who first raised the issue.

The Prime Minister attempted to defuse the situation, telling reporters: "I have been able to tell Nicolas that I don't believe everything that I read in the British press."

And a now smiling Mr Sarkozy then quipped: "I love England - don't make me regret it".

Ms Bruni has accompanied her husband on a visit to London once, on a state occasion, since he became president.

But even under normal circumstances she would be unlikely to join him on the type of visit he is undertaking to the UK.