PARIS (AFP) - French police have searched the headquarters of BNP Paribas bank as part of a probe linked to Wall Street fraudster Bernard Madoff, a judicial official said Thursday.

Investigators from the financial police seized documents during the search on March 26 at the Paris offices, said the official.

French prosecutors last month opened a preliminary inquiry into BNP Paribas after a suit was filed against the French bank for alleged forgery and use of forged documents.

Lawyer Olivier Metzner brought the lawsuit on behalf of a client who lost two million euros (S$4 million) in a fund linked to Madoff, who faces up to 150 years in jail for running a multi-billion-dollar Ponzi scheme.

"Madoff did not act alone. He couldn't have done what he did without banks acting as a relay," Metzner told AFP.

"BNP was managing and dealing in Madoff products," he said.

A spokesman for BNP Paribas confirmed its headquarters had been searched, saying the bank "was asked by police to produce documents and explanations in response to a lawsuit.

"We answered their demands in full transparency," he told AFP, but added that "BNP Paribas considers this lawsuit to be totally artificial" and that the bank has filed suit for defamation with the Paris prosecutor's office.

Three preliminary investigations have been opened in France following complaints from investors who say they were conned by Madoff, who has been jailed for fraud, money laundering, perjury and theft in the United States.

The 70-year-old broker is to be sentenced in June.

France's financial market regulator the AMF said in December that around 100 French investment funds could be affected by the scandal, with losses to the tune of half a billion euros.