Spies Reported Inside Contra Bases : Sandinista Agents Infiltrated Headquarters, Sources Say

U.S.-backed Nicaraguan rebels have discovered at least 12 suspected agents of the leftist Managua government working as spies and saboteurs inside the contras’ main bases, including two paramedics who may have killed contra commanders under their care, U.S. and rebel officials said Friday.

The suspected Sandinista agents also included spies who transmitted intelligence to Nicaragua from the contras’ secret air base in Honduras by clandestine radio undetected for more than three years and others who infiltrated the contras’ military and political headquarters, including the chauffeur of a top rebel official.

And at least one Sandinista infiltrator fought alongside contra troops to prove his loyalty but is now suspected of shooting a contra commander in the back, the officials said.

“We have had infiltrators before . . . (but) this may have been the biggest cell we’ve found,” a senior contra official said. “They were very, very sophisticated. They had a direct communications link to the Sandinistas from within.”

‘Extremely Sophisticated’

“It was a systematic sabotage operation in effect since 1983,” a knowledgeable U.S. official said. “It was extremely sophisticated, very well done, and done over a long period of time.”

One American official said that the damage done by the spy network may have been “devastating” to the rebels’ military fortunes. Others said that the damage still is being assessed, and one said that it appeared to be only “moderate.”

“We knew there were infiltrators, but we did not know that they were in such sensitive places,” one rebel official said.

Contra leader Adolfo Calero refused to comment on the reports, although an aide acknowledged that they are true. Some rebel officials appeared embarrassed by the discovery that their most important bases had been infiltrated by enemy agents.

The contras have also attempted to infiltrate spies and saboteurs into Managua, but U.S. and rebel officials say they have had little success.

Accidental Discovery

One rebel leader said that the contras uncovered the Sandinista operation by accident last month, when a contra killed an intruder and found, on his body, a scrap of paper with the name of a person at the Aguacate air base in Honduras. U.S. officials said they were unable to confirm that account.

Both U.S. and contra officials said that the rebels, assisted by the CIA, are still trying to determine whether more spies are in their midst.

Asked about the fate of the suspects arrested so far, a U.S. official said: “No one’s been killed. The principal has been arrested and interrogated, and he’s leading them to the others.”

Officials said the suspected spies include:

--The two paramedics, at least one of whom is said to be a woman suspected of surreptitiously cutting off the supply of oxygen to wounded contras during surgery. “We are looking at several suspicious deaths,” a contra official said.

--A man who worked as a chauffeur for Aristides Sanchez, a director of the largest contra faction, at the rebels’ political headquarters in Tegucigalpa, the Honduran capital.

--Another who fought as a contra and even lost two fingers in combat--but is now suspected of shooting his commander in the back. “We have had a lot of stray bullets, and we didn’t know if they came from the Sandinistas or from infiltrators,” a rebel official said.

--An agent who managed to infiltrate the contras’ most sensitive strategic base, their military headquarters at Yamales on the Honduras-Nicaragua border.

--Several agents at Aguacate who observed rebel supply flights for the Sandinistas and occasionally attempted to destroy airplanes and weaponry. “One plane was pretty badly sabotaged, but it wasn’t a total loss,” a U.S. official said.

“Amazingly, even though they had real-time monitoring (observing and instantly transmitting data) of the flights out of Aguacate, nobody got shot down,” he added. The crash of a contra supply flight last October, which killed three crewmen and delivered a fourth, Eugene Hasenfus, into the hands of the Sandinistas, “wasn’t related to this at all,” he said.

He said that the contras’ small counterintelligence squad, on CIA advice, had long been looking for Sandinista infiltrators. “There were indications for a good long time that something was wrong,” he said. “Some things were being sabotaged, for example. They were able to come to the conclusion from that that there were people inside.”

An American crewman who worked on the secret U.S. airlift for the contras last year said that he was warned about saboteurs when he first arrived at Aguacate in April, 1986, more than a year ago.

“I was warned that there were three infiltrators--a doctor, a pilot and one other--but they didn’t know who they were,” the crewman, Iain Crawford, said.

Difficult Time

The arrest of the suspected spies comes at a difficult time for the contras on several fronts. The rebels have been struggling to demonstrate effectiveness in the battlefield before Congress debates a Reagan Administration request for $105 million in new military aid.

At the same time, the rebels have been plagued by political divisions--not only among their top leaders, but also among combat commanders, who include both former Sandinistas and former officers in the army of the late Nicaraguan dictator, Anastasio Somoza.

“The old Somocistas are always accusing the ex-Sandinistas of being spies,” one U.S. official said. “These infiltrators are real--at least, as far as we know, they are--but there’s always the chance that someone could be unfairly accused.”

Times staff writer Marjorie Miller, in Miami, contributed to this article.