Federal prosecutors told a judge in a filing late Tuesday night that they have evidence that former WorldCom Inc. chief executive Bernard J. Ebbers knew company officials had improperly tinkered with the telecommunications firm's accounting to boost its publicly reported profits.

WorldCom's former chief financial officer, Scott D. Sullivan, has pleaded guilty to fraud for his role in the nation's largest accounting scandal. Ebbers's role in the troubles at WorldCom, which entered bankruptcy protection in 2002, long has been unclear.

Ebbers's lawyers sought immunity this month for WorldCom's former chief operating officer, Ronald R. Beaumont, and another executive, saying they could help clear Ebbers. But the U.S. attorney's office in Manhattan argued in a response filed Tuesday that Ebbers would not be helped by testimony that the two men had never discussed with him the decision to treat "opportunities" to earn revenue as revenue already earned, and other alleged machinations.

"The government intends to introduce evidence that will directly prove Ebbers' knowledge on this issue," Assistant U.S. Attorney David Anders wrote.

Ebbers has pleaded not guilty to conspiracy, securities fraud and filing false documents with the Securities and Exchange Commission. His lawyer Reid H. Weingarten did not respond to phone and e-mail messages; previously he has said Ebbers was unaware of wrongdoing at WorldCom.

Prosecutors also urged U.S. District Judge Barbara S. Jones to turn down Ebbers's request to delay his November trial and move it to Mississippi, where the company was once headquartered. The firm is now based in Ashburn and does business as MCI Inc.

Former WorldCom CEO Bernard J. Ebbers is to go on trial in November.