Sarkozy is accused of trying to illegally obtain information from a magistrate about an investigation involving him in 2014.

He'll be tried in Paris along with his lawyer Thierry Herzog, 65, and the magistrate, Gilbert Azibert, 73.

They face a prison sentence of up to 10 years and a maximum fine of one million euros ($A1.6 million) . They deny any wrongdoing.

Sarkozy and Herzog are suspected of promising Azibert a job in Monaco in exchange for leaking information about an investigation into suspected illegal financing of the 2007 presidential campaign by France's richest woman, L'Oreal heiress Liliane Bettencourt.

In 2014, Sarkozy and Herzog used secret mobile phones to have private talks.

Judges have found that discussions between Sarkozy and his lawyer suggested they had knowledge that judicial investigators at the time tapped their conversations on their official phones, as they mentioned "judges listening".

Sarkozy argued that he had never intervened to help Azibert, who never got the job and retired in 2014.

Sarkozy has claimed judicial harassment, accusing judges of breaching lawyer-client privilege via wire-tapping.

The former president's name has appeared for years in several other judicial investigations.

Allegations, which include illegal financing of his 2007 campaign by then-Libyan dictator Muammar Gaddafi, cast a shadow over Sarkozy's comeback attempt for the 2017 presidential election.

After failing to be chosen as a candidate by his conservative party, he withdrew from active politics.

Meanwhile, the former president will stand another trial in spring 2021 along with 13 other people on charges of illegal financing of his 2012 presidential campaign.

His conservative party and a company named Bygmalion are accused of using a special invoice system to conceal unauthorised overspending.

Sarkozy remains the most popular figure amid French right-wing voters in recent years. His memoirs published this summer, The Time Of Storms, was a bestseller for weeks.

Australian Associated Press