French President Nicolas Sarkozy delivered a thinly-veiled swipe at David Cameron as he insisted Britain must remain "bang in the middle" of Europe.
Following talks with Gordon Brown in Downing Street, Mr Sarkozy insisted he was not in Britain to "play politics" ahead of the forthcoming general election.
But he took aim squarely at the Tory leader when he expressed "regret" at his decision to pull out of the centre-right European People's Party grouping in the European Parliament.
"I remain convinced that the position of our British friends is bang in the middle of Europe," Mr Sarkozy told a joint press conference with Mr Brown. "We need you."
The EPP issue was raised again "in passing" when Mr Sarkozy held a meeting with Mr Cameron. However, a spokeswoman for Mr Cameron insisted the discussions had been "very good", and they had both signalled they wanted their countries to co-operate more closely.
The apparent spat came as rumours over the French president's marriage to singer and ex-model Carla Bruni threatened to overshadow his visit.
Mr Sarkozy angrily dismissed questions about unsubstantiated allegations that both were having affairs, seeming to suggest he was too busy with presidential duties to pursue other women.
The Tories have come under fire for recruiting MEPs from several far-right parties to form an alternative grouping in the European Parliament but it was unclear whether Mr Brown was making a direct criticism.
Asked if he would urge Mr Cameron to rejoin the European People's Party (EPP), Mr Sarkozy said: "I don't want to meddle in domestic affairs. If you ask me whether I would have preferred him to stay in the EPP - my answer is yes."
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He pointed out that he took his own party into it. "But that having been said, I have enough problems to deal with at home without taking on other people's. But opening up is a good thing."
