Former French President Nicolas Sarkozy has been ordered to stand trial for influence peddling over accusations he offered to help a prosecutor get promoted in return for leaked information about a separate criminal inquiry.

Mr Sarkozy, who is embroiled in several criminal investigations, denies any wrongdoing and has vowed to have all cases dismissed.

His lawyers said they would appeal today’s decision to try him.

"Nicolas Sarkozy will... calmly wait for the result of the motion for a declaration of invalidity. He does not doubt that once again the truth will triumph," his lawyers said in a statement.

His appeal will be heard on 25 June, it said.

The case came about after investigators used phone-taps to examine separate allegations that late Libyan leader Muammar Gaddafi funded Mr Sarkozy's campaign.

The investigators began to suspect the former president had kept tabs on a separate case through a network of informants.

The development came just over a week after the 63-year-old was told he was being formally treated as a suspect in the election campaign investigation.

Mr Sarkozy was president from 2007 to 2012 but was defeated by Socialist Francois Hollande when he ran for re-election.

He has since faced a series of investigations into alleged corruption, fraud, favoritism and campaign-funding irregularities.

Under French law, a suspect is not formally charged with a crime unless he is sent to trial.

Mr Sarkozy’s lawyers had previously argued that magistrates investigating the alleged secret Libyan funding exceeded their powers and went on a fishing expedition by tapping his conversations between September 2013 and March 2014, breaching lawyer-client privilege.

He used the mobile phone account under the alias Paul Bismuth only for calls with lawyer Thierry Herzog.

Based on the intercepts, Mr Sarkozy, who still had political influence at the time despite having left office, is accused of having discussed offering a promotion to a prosecutor in return for tip-offs on another campaign funding probe.

That investigation, into accusations that Mr Sarkozy's former party treasurer Eric Woerth and others exploited the mental frailty of Frances richest woman, Liliane Bettencourt, to extract political donations, was dropped without charges.

A source close to the investigation said that along with Mr Sarkozy, Herzog, and the prosecutor would also face trial on the same charges.

Influence-peddling can be punished in France by up to five years in prison and a fine of €500,000.

Mr Sarkozy lost presidential immunity from legal prosecution a month after he left office in June 2012.