The Philippine Supreme Court rejected a petition today for a retrial of 26 persons on charges growing out of the 1983 assassination of opposition leader Benigno Aquino. The ruling appeared to bring closer the announcement of a lower court's verdict on the case.

In a 9-to-2 decision, the Supreme Court rejected with no hearing the petitioners' contention that judges and prosecutors had shown bias toward the defendants, all but one of whom are military personnel, during the seven-month trial.

The lower court had been about to make public its verdict earlier this month but was ordered to withhold it until the Supreme Court considered the petition, filed by a group of prominent Filipinos, including three former Supreme Court justices.

Chief Justice Ramon Aquino, a former law school classmate whom Marcos appointed chief justice last week and who is not related to the slain Aquino, voted to dismiss the petition, saying it was "utterly devoid of any legal basis whatsoever."

A lawyer for the petitioners, Arturo de Castro, said today that they will appeal the Supreme Court's ruling within the required 15 days. Disclosure of the trial verdict, meanwhile, will remain barred while the justices consider that appeal.

The defendants in the Aquino trial include the suspended armed forces chief of staff, Gen. Fabian Ver, a cousin and close confidant of President Ferdinand Marcos. He is widely expected to be acquitted because the Supreme Court disqualified most of the evidence against him in an earlier decision