The boss of French oil giant Total is being questioned by police as part of a probe into alleged corruption in Iran.
Mr de Margerie was placed under investigation last year
Total said Christophe de Margerie and two employees were being interviewed about the firm's role in the South Pars natural gas project in Iran.
The company said it was "confident" the investigation would not uncover any illegal activities.
The inquiry concerns allegations that illegal payments were made to win the gas contract in 1997.
Mr de Margerie was also placed under investigation last year over claims he paid bribes to win bids in Iraq.
Between 1995 and 1999 he headed Total's Middle East operations, then became head of exploration and production before taking the role of chief executive.
"Total is confident in the fact that (the) investigation will establish the absence of any illegal activities and hopes that it will be conducted with serenity," the oil giant said in a statement.
A number of global figures have been caught up in the so-called Iraq oil-for-food scandal.
A French judge is investigating claims that Mr de Margerie paid illegal kickbacks to win favours for his company between 1996 and 2002.
The oil-for-food scandal damaged the reputation of former UN Secretary General Kofi Annan, who took personal responsibility for failures at the programme last year.