The Paris offices of UBS have been searched as part of a probe into tax evasion, a spokesman for the Swiss bank said on Wednesday, adding that it was cooperating with the investigation.
The evidence-gathering move was part of a broader enquiry which saw the bank's offices in Bordeaux, Strasbourg and Lyon searched in July.
Agence France Presse, citing a source, reported that the search, carried out by an examining magistrate, was part of a probe into covering up tax evasion in which two people had already been placed under investigation.
The search was carried out by about 10 investigators from France's National Customs Service, Agence France Presse said.
Concerns about wealthy French citizens trying to shelter their funds from taxes have been on the rise in recent months, with a Senate committee dedicated to tax evasion and money laundering questioning several prominent bankers earlier this year.
UBS' own wealth management practices earlier this year were the subject of a book entitled "Those 600 billion that France is missing", which alleged that its French unit sheltered an average of 85 million euros ($111 million)of client funds a year from taxes.
(Reporting by Katharina Bart and Christian Plumb; Editing by James Regan)