RICHMOND, Va. (AP) _ The tax and mail fraud conspiracy conviction of Lyndon H. LaRouche Jr. was challenged Friday in a federal appeals court as a rush job that violated the political maverick's due process rights.

But the prosecutor said LaRouche's attorneys failed to show prejudice in the handling of the case.

LaRouche, a political extremist who has espoused bizarre conspiracy theories that include allegations of drug-dealing and other crimes by world leaders, was convicted in December in U.S. District Court in Alexandria on 11 counts of mail fraud, one count of conspiracy to commit mail fraud and one count of conspiracy to defraud the Internal Revenue Service.

The trial of LaRouche and six associates stemmed from more than $30 million in loans raised by LaRouche's political supporters. The government said LaRouche had no intention of repaying the loans and avoided taxes by reporting no income and having his personal expenses paid through corporations he controlled.

Former Attorney General Ramsey Clark, chief attorney for LaRouche's appeal, told a three-judge panel of the 4th U.S. Circuit Court of Appeals that trial Judge Albert V. Bryan Jr. allowed only 35 days from arraignment to trial and, once the proceedings began, failed to adequately question jurors on how much they knew about LaRouche.

''It was just an incredible rush,'' Clark said. ''You just have to ask why.''

The appeals panel did not rule immediately. Decisions from the court usually take from a few weeks to several months.

Odin Phillips Anderson, another lawyer for LaRouche, said the defense chose not to antagonize Bryan by requesting a delay but pushed to have the trial moved to Boston, where a similar case against LaRouche had resulted in a May 1988 mistrial. The Boston charges were dropped after the Alexandria case was concluded.

''LaRouche is 67 years old,'' he said. ''He's sentenced to 15 years. Surely if this case isn't reversed, it's a death sentence.''

U.S. Attorney Kent S. Robinson II said the ''substantial overlap'' in the Boston and Alexandria cases and the effort to move the trial showed that LaRouche's lawyers were well acquainted with the issues before the court.

''There's just no showing that the defendant's lawyers were unable to try this case,'' he said, adding that government witnesses were thoroughly and extensively cross-examined.

Robinson also said Bryan was careful to prevent irrelevant information about LaRouche's political views from getting into testimony. He said the judge also questioned potential jurors about their awareness of news reports concerning LaRouche, and those who showed bias were dismissed.