The couple have appeared together less frequently recently Profile: Cecilia Sarkozy

One newspaper said the couple had appeared before a judge on Monday to begin formal divorce proceedings.

Mr Sarkozy's spokesman refused to comment on the story or the speculation, which has been circulating in the French media for weeks.

Mrs Sarkozy was once one of her husband's closest advisers, but has lately often been absent from his side.

She played only a small part in his election campaign earlier this year, and they have rarely been seen together since.

Mrs Sarkozy has said she is not interested in the role of first lady.

The French weekly Le Nouvel Observateur said on its website on Wednesday that the pair saw a judge on Monday to discuss details of a divorce.

The LCI TV channel said Mrs Sarkozy applied to a judge for a divorce and that later the judge visited the Elysee, the president's residence, to see Mr Sarkozy to validate the procedure.

The French constitution decrees that no criminal or civil proceedings can be brought against a sitting president - so Mrs Sarkozy could not file for divorce without Mr Sarkozy's consent.

Turbulence

The couple, who were both previously married, were wed in 1996 but have had a turbulent relationship.

The Sarkozys have been separated before

They separated for several months in 2005 when Cecilia eloped to New York with an advertising executive.

They were reconciled afterwards, but not completely reunited, it seemed, as Mrs Sarkozy avoided public appearances.

She appeared with her husband at a Bastille Garden party in July, but she has often been absent.

This summer she failed to accompany her husband to a picnic lunch hosted by US President George W Bush and last weekend she was again absent from her husband's side at France's Rugby World Cup match against England.

But there has been no official confirmation of a split.