Federal prosecutors yesterday urged a judge to send former WorldCom Inc. chief executive Bernard J. Ebbers to prison while his appeal wends through the justice system.

Ebbers, 63, is seeking to delay an Oct. 12 deadline to report to a federal prison in Yazoo City, Miss., while he appeals his fraud, conspiracy and false statements conviction.

Last month, U.S. District Judge Barbara S. Jones imposed a 25-year sentence on the former telecommunications mogul, virtually ensuring that Ebbers would spend the rest of his life in prison. Under the federal system, inmates must serve at least 85 percent of their sentence -- making Ebbers eligible for release after two decades.

Defense lawyers Reid H. Weingarten and Brian M. Heberlig vowed to appeal the conviction, citing what they called erroneous jury instructions and the judge's refusal to transfer the case to Mississippi, where WorldCom was based. The defense team also took issue with the lengthy prison sentence.

To keep Ebbers out on bail during the appeal, defense lawyers must show that he will not flee the country and that he has a substantial chance of winning a new trial or reversal of the conviction.

Assistant U.S. Attorney David B. Anders argued that Ebbers had not met that high burden in a brief filed with the court yesterday.

"The applicable standard of review for each of these issues makes reversal highly unlikely and thus bail pending appeal is unwarranted," Anders wrote.

WorldCom's collapse after an $11 billion accounting fraud led to the nation's largest-ever bankruptcy filing in 2002. The Ashburn company has since emerged from bankruptcy and renamed itself MCI Inc.

Two former WorldCom accounting workers, Betty L. Vinson and Troy M. Normand, pleaded guilty to taking part in the fraud and are scheduled to be sentenced tomorrow. Onetime finance chief Scott D. Sullivan, whom prosecutors described as their star witness against Ebbers, will face sentencing later this month.

In the current round of corporate fraud cases, judges have a mixed record of granting defense requests to stay prison terms pending appeal.

John J. Rigas, the 80-year-old founder of Adelphia Communications Corp., won a bid to delay his 15-year prison sentence. So did former Credit Suisse First Boston LLC investment banker Frank P. Quattrone, who is appealing his obstruction-of-justice conviction. Domestic entrepreneur Martha Stewart chose to report to prison in October even though she could have remained free while her appeal of a false-statements conviction was pending. At the time, Stewart said she wanted to move on with her life.

But former Merrill Lynch & Co. vice chairman Daniel H. Bayly reported to a federal prison in Hopewell, Va., last month after a judge denied his bid to remain free -- even as his lawyers petitioned an appeals court for expedited review of his case. A Houston jury convicted Bayly and other former Merrill officials of entering into a 1999 sham deal that helped Enron Corp. disguise its mounting financial troubles. A federal judge sentenced Bayly to a 30-month prison term.

Bernard J. Ebbers has an Oct. 12 deadline to report to prison. He's trying to delay it as he appeals his convictions.