The boss of Total has been placed under judicial investigation as police step up their probe into alleged corruption involving the French oil firm in Iran.
Christophe de Margerie was interviewed on Wednesday about claims of illegal payments made to secure a natural gas deal with Iran in 1997.
Being put under judicial investigation is the first step to formal charges.
Mr de Margerie has denied wrongdoing and Total says it is "confident" nothing improper will be uncovered.
Mr de Margerie was released without bail on Thursday having spent the previous night in custody.
Reuters and Agence France Presse quoted judicial sources as saying Mr de Margerie was under investigation for "corruption of foreign officials" and "misuse of company assets".
Under French law, placing someone under judicial investigation identifies them as an official suspect but does not guarantee that charges will be brought.
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 last month.
The investigation centres around allegations of kickbacks paid to win a contract with the Iranian government to operate the South Pars gas contract.
Total said the firm was continuing to function normally and that it fully supported its chief executive.
"Once again, the group expresses its full support for its employees and confirms that the agreements for the development of the South Pars project were entered into in compliance with applicable law," the firm said.
Mr de Margerie was also placed under investigation last year over allegations that he paid bribes to win bids in Iraq.
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.
(BBC News, 22/03/2007)