Police acting on a judge's instructions have searched the offices of the French Finance Minister, Thierry Breton.
Thierry Breton became finance minister this month
The investigation is reported to be linked to a probe into the accounts of French chemicals firm Rhodia, where Mr Breton was previously a board member.
Mr Breton, appointed finance minister on 2 June, is on a visit to the US.
The authorities are investigating claims of inaccurate accounting and insider trading at Rhodia between 1999 and 2002.