SAN SALVADOR, DEC. 29 -- An appellate court freed two men convicted of the 1981 murder of two American land reform advisers and a Salvadoran official, refusing to accept appeals under a sweeping amnesty program enacted as part of a regional peace plan, judicial and prison sources said today.

A lower court ruling that the men were covered by the amnesty and should be freed had been appealed by the attorney general with the support of the U.S. Embassy.

Judicial sources said the ruling was handed down Dec. 19, and the men freed the same day, just hours before the courts entered a three-week recess -- hence cutting off normal access to the bench for confirmation of its action. This maneuver was made, according to the sources, in an attempt to mitigate the ruling's impact in the United States.

The ruling also closed the case against a cashiered Army officer who has been accused of having ordered the murder, according to the lawyers involved in the case. The officer, Eduardo Avila, was a protege of rightist leader Roberto d'Aubuisson.

The amnesty was declared Nov. 5 by President Jose Napoleon Duarte as part of a regional peace plan. Amnesty was given for any political crime, closing the books on thousands of assassinations in the early 1980s in El Salvador's bloody civil war. Some 480 political prisoners were freed under the plan, most of them suspected sympathizers of leftist rebels.

Luis Arevalo Rivas, defense lawyer for the two convicts in the land-reform case, told reporters today that the release order was issued Dec. 19, and that the men had been freed from the Mariona maximum security prison shortly afterward.

The report was confirmed by a reliable judicial source and an officer at the prison, who said family members picked up the two men at the prison. The prison officer, Capt. Vitelio Escobar, said he did not know where the men were taken by their families.

The murders were among the most notorious by El Salvador's right-wing death squads and came as the government, supported by the United States, was beginning to implement a sweeping land reform that stripped the landed rich of much of their economic base and infuriated the militant far right.

The U.S. Embassy, which has followed the case closely for six years, said it had not been informed of the men's release, and could not confirm or deny the information.

"The heart of the ruling is that no appeals are valid under the amnesty law, so the original ruling stands," Arevalo Rivas said. "The case is now closed, my clients are free, and the cases against others mentioned in the crime are closed."

On Jan. 3, 1981, Americans Michael Hammer of Potomac, Md., and Mark Pearlman of Seattle, along with Jose Rodolfo Viera, in charge of the Institute of Agrarian Transformation, were killed at a hotel coffee shop. Hammer and Pearlmen worked with the AFL-CIO's American Institute for Free Labor Development.

Five years later, Jose Dimas Valle Acevedo and Santiago Gomez Gonzalez, who had confessed, were sentenced to 30 years in prison for aggravated homicide, the maximum sentence here.

Both men, who were serving in the National Guard when they carried out the killings, said that former lieutenent Rodolfo Isidro Lopez Sibrian had ordered the murder and that Avila was present and approved it. But under Salvadoran law, the testimony of one person implicated in a crime is not valid against another charged in the same crime.

Avila was detained briefly but ordered released by the Supreme Court, where his uncle sits. Repeated U.S. efforts to move that case forward produced few results, and it, too, is now closed.

Lopez Sibrian was arrested last year for participating in a kidnaping ring. On Dec. 12, the Fifth Criminal Court ruled the case fell under the amnesty and ordered the men released. They were held as the ruling was appealed by the attorney general, with U.S. support.

"It was so clearly a political murder, there could really be no appeal," said a judicial source who studied the case extensively.