In 2014, Nicolas Sarkozy became the first former French president to be taken into police custody. (File)

Former French President Nicolas Sarkozy on Monday lost a first appeal against facing trial over influence peddling and corruption charges and must await a second appeal before knowing if he will be sent to court, the Paris prosecutor's office said.

Sarkozy, who was president from 2007 to 2012, is suspected of helping a prosecutor get promoted in return for leaked information about a separate criminal inquiry.

Investigators were using phone-taps to examine allegations that late Libyan leader Muammar Gaddafi funded Sarkozy's election campaign when they began to suspect the former French leader had used a network of informants to keep tabs on the criminal case.

It was unclear when the next appeal decision would come.

Sarkozy was defeated by Socialist Francois Hollande when he ran for re-election in 2012. 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. Influence-peddling can be punished in France by up to five years in prison and a fine of 500,000 euros ($682,000).

Sarkozy lost presidential immunity from legal prosecution a month after he left office.

© Thomson Reuters 2018