SAN SALVADOR, FEB. 5 -- A military appeals court has asked President Jose Napoleon Duarte to decide whether three suspected participants in the 1985 slaying of four U.S. marines and eight civilians are covered by his government's controversial amnesty.

In a decision yesterday afternoon, the appeals court, which last month upheld a lower court decision to free the men, rejected an appeal by the attorney general to have the case reviewed by the Supreme Court.

"The case is only appealable to the commander-in-chief of the armed forces, and it is up to him to ratify or reject our ruling," said court secretary Rene Samuel Valdivieso. "We believe our ruling was correct and reject the appeal of the attorney general. We have passed the case on to the president, and he will have the final word."

The case is delicate because it involves Americans. If the men are freed, El Salvador automatically loses $18.5 million in U.S. economic aid. The provision was written into U.S. legislation.

The United States said the original decision to free the three suspects was "morally wrong and politically damaging," and has promised to use every legal means to keep them in jail. There was no comment on the decision to turn the case over to Duarte.

Duarte has said repeatedly that his amnesty, enacted Nov. 5, was meant to be as broad as possible, to comply fully with the Central American peace plan.