Celebrity lawyer Michael Avenatti was arrested on Tuesday on accusations that he violated the terms of his release from custody while awaiting trial on charges that he sought to extort millions of dollars from Nike Inc., federal prosecutors said.

Avenatti, 48, whose trial in the Nike case is set to start next week, was taken into custody by agents from the Internal Revenue Service, said Thom Mrozek, a spokesman for the U.S. attorney’s office in Los Angeles.

Mrozek said that he could not discuss the allegations that led to Avenatti’s arrest because the documents had been sealed by a judge. An arrest warrant filed in U.S. District Court in New York does not spell out the accusations.