(CNN) Fashion tycoon Peter Nygard's New York office was raided Tuesday as the magnate faces allegations of sex trafficking in a civil lawsuit.

The FBI and New York police executed the search warrant, said Nicholas Biase, a spokesman for the US Attorney's Office for the Southern District of New York.

Nygard's spokesman Ken Frydman said authorities executed search warrants on Nygard's offices in New York and California, and he said his client is "not surprised" by the raids.

"Nygard welcomes the federal investigation and expects his name to be cleared," Frydman said. "He has not been charged, is not in custody and is cooperating with the investigation."

He later announced Nygard will step down as chairman and will divest his ownership interest.

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