Former French president Nicolas Sarkozy has been placed under formal investigation following allegations of influence peddling.

The 59-year-old was kept in police custody for 15 hours at Nanterre, on the western outskirts of Paris, before reportedly arriving at the civil court in the French capital to meet with judges late Tuesday evening.

In France, if a suspect is placed under formal investigation, he or she is examined by a judge, who determines whether there is sufficient evidence for the accused to be charged. The step, which often but not always leads to trial, might ruin Sarkozy’s political career.

If found guilty of corruption and misuse of influence, Sarkozy could face up to five years in prison and a fine of 500, 000 euros (£400, 000).

The ex-president has been accused of inappropriately using his power to obtain details of a police investigation concerning irregularities in his victorious 2007 election campaign.

Police initiated the investigation following suspicions that Sarkozy obtained illegal donations to fund his 2007 campaign from L’Oreal heiress Liliane Bettencourt and former Libyan dictator Muammar Gaddafi.

One of the investigative measures employed by the police was tapping Sarkozy’s phone. Officers claim it was during a conversation between Sarkozy and his lawyer Thierry Herzog, the pair was overheard discussing the retrieval of information regarding the investigation. The duo wanted to offer a senior prosecutor Giles Azibert a more high-profile role in Monaco in return of the legal information. Azibert and Herzog were also detained in relation to the allegations.

Supporters of Sarkozy strongly condemn the use of phone-hacking by the police. Herzog’s lawyer Paul-Albert Iweins described the measure as “perfectly unjustified” and stated in a French newspaper Le Figaro: “It is a matter of a discussion between two friends that has been misinterpreted, there has been no active corruption. No money has been transferred.”

The present investigation, one of six in which Sarkozy is currently embroiled, comes as a serious knock to the former president’s hopes of retaining presidency in 2017 as UMP (Union for a Popular Movement) leader.

Sarkozy will reportedly appear tonight on French national television to offer his countrymen an explanation for his suspected corruption. The appearance will be Sarkozy’s first public interview since ceding the presidency two years ago.