Former French president Nicolas Sarkozy has been placed under preliminary investigation for "influence peddling," French media reported on Friday.

The former head of state is under scrutiny for advisory work he undertook for a Russian insurance company, the reports said. Judiciary sources confirmed the launch of the investigation to the Deutsche Presse-Agentur (dpa) but declined to give details.

Separately, Sarkozy – who was in power from 2007 to 2012 – is on trial on charges of bribery and illicit influence. The prosecution has demanded a sentence of four years in prison and a verdict is expected on March 1.

Sources close to the former head of state have stated that Sarkozy's advisory activities complied with legal and professional ethical rules, according to a report from Agence France-Presse (AFP).