Two men recently arrested for suspected involvement in the slaying of two American agricultural advisers and a Salvadoran land reform official in January originally were sought by Salvadoran authorities primarily for plotting a right-wing coup, U.S. officials said yesterday.

U.S. officials said the two men, Ricardo Sol Meza, arrested two weeks ago in El Salvador, and Hans Christ, arrested Wednesday in Miami Beach, allegedly had been implicated for some time in the killing of the two Americans, Michael Hammer, 42, of Potomac, and Mark Pearlman, 36, of Seattle, both working for an AFL-CIO project advising the Salvadoran land reform program. Also shot down with the two Americans was Rodolfo Viera, head of a peasant union and of the land reform program.

But Sol Meza, one of the wealthiest men in El Salvador, reportedly was arrested April 5 by police there only after he had been overheard the night before advocating a coup against the shaky civilian-military ruling junta headed by President Jose Napoleon Duarte, these sources said.

The day after that arrest, Christ, Sol Meza's brother-in-law, also believed by authorities to be involved in the coup conspiracy, arrived in Miami. On April 10, Salvadoran authorities asked that Christ be extradited to El Salvador on murder charges. Christ was arrested by FBI agents in Miami Beach and is being held in Dale County jail.

Both men are supected of having ties to right-wing groups bitterly opposed to the Salvadoran land reform program, according to U.S. sources. Christ's father, who has apparently left El Salvador, reportedly owned a huge cotton plantation taken over by the government.

Many landowners there have lost their estates as a result of the land redistribution program, which is backed by the U.S. government as a means to secure broad-based support for the ruling junta in its struggle against left-wing guerrillas. Duarte, accused by the right wing of being a communist, has blamed rightists for hundreds of killings of both moderate and leftist civilians. Duarte has said that the three men, who were gunned down in a hotel coffee shop on Jan. 3, were killed by right-wing forces.

At least one other man is being sought for involvement in the killings and three others may be involved at least as conspirators.

U.S. sources also said there are indications that the killings may not have been a careful plot but rather a spur-of-the moment decision on the part of the slayers.

The sources said the two Americans and Viera entered the Sheraton Hotel for a late dinner and were seated near a group of six men, all known as members of the Salvadoran oligarchy. Sol Meza reportedly owns an interest in the Sheraton.

Both groups immediately recognized each other. Although Hammer had just arrived in El Salvador and was only going to spend one night there, he was well-known -- and hated -- by the landed oligarchy as one of the main architects of the land reform. According to a close friend, Hammer had registered in the hotel under an assumed name and had booked two separate rooms for security reasons.

The trio moved to another table out of earshot of the other group, which left a short time later. Shortly after that, two gunmen came in and shot the trio with automatic weapons.

U.S. sources said it was possible that Salvadoran authorities discovered some evidence in Sol Meza's home when they arrested him, which would further tie him or the other men sought to the killings. But, those sources said, there are numerous witnesses who apparently saw him and Christ and the others at the hotel both before and after the shootings.

One of those witnesses, according to a Justice Department source, has been brought to the United States for her own security. "Those men have a lot of friends down there," the source said.

A spokesman for the U.S. attorney's office in Miami said the government would oppose any bail for Christ, whose hearing is set for today. The Salvadoran government has two months to produce documentation to justify Christ's extradition to El Salvador.