SAN FRANCISCO -- The FBI and the CIA are investigating the possibility that a Cuban spy working for the Fidel Castro government in the United States was linked to a plot to kill President Ford and Republican presidential contender Ronald Reagan.

The Chicago Tribune quoted U.S. Justice Department sources here as stating that the man under investigation is Andres Gomez. According to the newspaper, federal agents have a lead that Gomez was linked with the Emiliano Zapata unit and may have added in plans for an assassination. The unit has claimed credit for numerous Bay Area bombings.

Informed of the report about Gomez, a source in law enforcement independent of the FBI told The Times:

"We never had a name, but the FBI told us it was looking into the possibility of a Cuban being involved with the Emiliano Zapata unit. But we were cautioned not to say anything about him because it was something involving national security."

This same source said it was his understanding that the Cuban had left the United States and that he may have somehow been wounded. This official had no further explanation of the wounding.

The Chicago Tribune said the Central Intelligence Agency is trying to determine if Gomez was in the United States at the time when a plot was supposedly being hatched to kill the President and Reagan, his Republican opponent for the Presidency.

The FBI had no comment on the report.

Earlier this week, The Times confirmed reports that Gregg D, Adornetto, 26, told the FBI that Bay Area radicals were plotting to assassinate Ford and Reagan at the Republican National Convention next August. The report about the Cuban apparently also came from Adornetto.

Some sources in the FBI and elsewhere in law enforcement are very skeptical, however, about how much stock to place in Adornetto's statements. He is one of six persons arrested in a raid on a house where FBI agents found explosives, an assembled bomb and documents linking the material to the Emiliamo Zapata unit.

What Adornetto is telling the FBI was thrown into further confusion Thursday when a document filed in federal court indicated that he is taking the blame for illegally possessing explosives and is absolving the other five of any responsibility.

A document filed by Asst. U.S. Atty. Malcolm Segal said that "Adornetto, originally a defendant and a joint venturer" with the others, has made statements which "tend to clear" them. He is scheduled to have a preliminary hearing Monday before U.S. Magistrate Richard Goldsmith on a charge of possessing an unregistered destructive device.

At the request of his attorney, Jerry Cimmet, Goldsmith recently ordered him to receive psychiatric tests. At the time the examination was ordered, Adornetto told the magistrate: "I was responsible for innocent people that are in custody" and said anything they did was done under his orders.

A law enforcement source said he had seen documents seized at the time the six were arrested.

"The documents indicate that Adornetto was part of the group but that others were more in command," this source said.