Two prosecutors who resigned from a probe into the 1989 massacre of six Jesuit priests say the army is standing in the way of the investigation, protecting those who plotted the murders.

"The discovery of the masterminds depends on the high command of the armed forces, who have known the facts well since the day they occurred," Edward Sidney Blanco told a news conference on Wednesday.The charges of an army cover-up came a few hours after the military's chief foe, the leftist rebel Farabundo Marti National Liberation Front, said it had arrested two members suspected of executing two captured U.S. soldiers.

At stake in the two cases is $42.5 million in U.S. military aid. The U.S. Congress last year suspended the aid to protest slow progress in solving the Jesuit murders and other human rights cases.

U.S. officials said that President Bush had decided this week to seek restoration of the aid. He was prodded partly by what officials called the "cold-blooded murder" of the two U.S. soldiers on Jan. 2.

Administration sources also cited continued arms shipments and continued military action by the rebels.

Blanco and Alvadro Henry Campos said they quit the attorney general's office because senior officials had prevented them from finding the true planners of the November 1989 slaying.

An investigating judge last month ordered a murder trial for a colonel and seven other soldiers in the slaying of six Jesuit priest-educators, their housekeeper and her 15-year-old daughter.

"Those who are detained are responsible, but they are not all," said Campos, echoing critics who have accused the army of protecting more senior figures.

"If there has been little credibility to the process so far, this wounds its credibility even more," said Monsignor Arturo Rivera Damas, Roman Catholic archbishop of San Salvador.

Campos told reporters that Attorney General Roberto Mendoza had forbidden investigators to seek the arrests of more soldiers or to requestion witnesses.

"It is known by all that the role of the armed forces is predominant and enforced and that it is difficult for a civilian administration to erase or modify it," he added.

Campos said the investigating judge "went as far as he could go, as far as he was permitted by the military, which did not hand over more people."