Another case in which Mr Sarkozy’s name has cropped up is the so-called “Karachi affair”, a complex investigation into alleged kickbacks on arms contracts.

Judges are looking into irregularities in the financing of former Prime Minister Edouard Balladur’s 1995 presidential campaign. Mr Sarkozy was Mr Balladur’s campaign spokesman and budget minister at the time.

Magistrates suspect the Balladur camp of receiving illicit “retro-commissions” from the sale of French submarines to Pakistan. Mr Sarkozy’s best man and former ministerial cabinet chief are both under formal investigation over the affair.

A separate investigation is under way into allegations that 11 French engineers died in a Karachi bombing carried out by Pakistani agents angry after bribes from the sale were cut off. Mr Sarkozy has always denied any wrongdoing.

The most recent corruption allegation to be levelled against him is that he received 50 million euros of illegal campaign contributions from the late Muammar Gaddafi.

Last month, investigative news website Mediapart published what it said was a copy of a document signed by Moussa Koussa, Col Gaddafi’s intelligence chief in 2006 outlining the alleged funding deal. Mr Sarkozy has dismissed it as a forgery.

Saif-Al Islam Gaddafi, Gaddafi’s son and former heir, last year unambiguously claimed that Libya had funded Mr Sarkozy’s election.

Finally, he could be questioned over why his former chef de cabinet signed a lucrative contract with an opinion poll company run by a close aide of the president without going through the normal public tender procedures.

Last December, Jacques Chirac became the first post-war French head of state to be convicted of criminal wrongdoing, receiving a two-year suspended prison sentence for diverting public funds and abusing public trust.