The investigation that resulted in this week's arrests of a CIA employe and her Ghanaian lover on espionage charges was touched off when the employe was given a polygraph test during a routine debriefing upon her return from Ghana, according to sources familiar with the case.

CIA officials, their suspicions aroused by the employe's responses, launched an internal investigation of Sharon M. Scranage, a low-level support assistant in the CIA's station in Ghana, sources said. The CIA inquiry uncovered allegations that the identities of CIA agents and their Ghanaian informants were passed on to Ghanaian intelligence officials, according to sources and FBI documents filed in federal court in Alexandria.

Sources said yesterday that Capt. Kojo Tsikata, the head of Ghanaian intelligence and a leader of the government's pro-Marxist faction, was one of the unidentified officials cited in an FBI account of a May 24 meeting Scranage allegedly had with Ghanaian officials. At the meeting, Scranage told the officals about secret CIA information she had previously divulged, and one asked her to learn the identities of three Ghanaian dissidents traveling abroad, according to FBI court documents.

In March 1983, Tsikata publicly accused the CIA of plotting to overthrow the government of Flight Lt. Jerry John Rawlings.

Tsikata is a radical leftist who is close to revolutionary regimes in Libya and Cuba, and he is considered the hard-line ideologue in Rawlings' regime, specialists said. He has been a close ally and adviser to Rawlings since the early 1970s, years before successive coups, in 1979 and 1981, put Rawlings in power.

Rawlings has maintained neutrality between the Soviet Union and the United States, using vitriolic Third World rhetoric while seeking western aid in the form of investment and International Monetary Fund loans, said Victor Levine, a Ghana expert who is a political science professor at Washington University at St. Louis.

"Ideologically, Rawlings considers himself to be not a communist but a disciple of Libyan leader Muammar Qaddafi," said Levine. Tsikata is Rawlings' hard-line "aide de camp" who "really dislikes the U.S.," Levine added.

Ghanaian dissident groups and academics specializing in Ghana echoed fears expressed by intelligence officials that, in part because of Tsikata's role, the classified CIA information allegedly compromised by Scranage was passed on to intelligence agencies of Libya, East Germany and other Soviet bloc nations.

"It will go to Libya, Cuba, East Germany, Russia and others," said Willie Bediaka Lamouse Smith, a leading Ghanaian dissident in this country and a professor of African-American studies at the University of Maryland's Baltimore County campus. "It's quite major damage."

Scranage has admitted to the FBI that she provided secret CIA data for about two years to Michael Agbotui Soussoudis, a relative of Rawlings and a Ghanaian national who prosecutors say is an operative of the Ghanaian intelligence service. Soussoudis, 39, who sources said was Scranage's lover, was arrested Wednesday night and has denied being a Ghanaian intelligence agent.

Scranage, 29, who is cooperating with the FBI, was formally charged Thursday. Both are being held without bail.

Besides the names of CIA agents and informants, Scranage passed on to Soussoudis the CIA's intelligence-gathering methods for its station in the Ghanaian capital of Accra and details about the CIA's radio and communications equipment, according to an FBI court affidavit.

The CIA has declined to comment on any aspect of the investigation or on the impact of Scranage's alleged disclosures on agency activities in Ghana. FBI spokesmen also declined to comment yesterday, as did the Ghanaian Embassy here.

Other government offficials familiar with the investigation said yesterday they did not know the impact of the alleged disclosures or whether the Ghanaians had shared information with other foreign intelligence agencies.

One government source said that at least one of the CIA's Ghanaian informants had disappeared, but it was not known whether any informants have been harmed as a result of the disclosures.

The CIA delayed turning over the case to the FBI, which is responsible for investigating the criminal aspects of espionage cases, in order to give CIA operatives time to leave Ghana and to alert Ghanaian informants, sources said.

On Wednesday, Soussoudis was lured by Scranage to a Springfield motel where he was arrested by waiting FBI agents, sources said. In separate hearings before a U.S. magistrate on Thursday, both were formally charged with conspiring to commit espionage, a crime that carries a maximum penalty of life in prison.

U.S. diplomatic sources said two years ago that Tsikata took part in a Soviet "disinformation" plot against the United States. In March 1983, Tsikata announced that the U.S. Embassy in Accra and the CIA were trying to overthrow Rawlings, and he produced as "proof" a copy of a West German Embassy report that then-U.S. Ambassador Thomas Smith was dissatisfied with the CIA in Ghana. The report said Smith ordered the CIA to get to work to overthrow Rawlings.

U.S. and West German officials branded the document a phony, and the Ghanaian government later acknowledged that it was. U.S. officials later said Tsikata's forgery was manufactured by the Soviets, part of a campaign of provocative fakes by the Soviet secret police in Africa.

Despite reports that the Rawlings government has distanced itself from Libya and East bloc nations in the last two years, dissidents say the ties remain strong. Last year, Tsikata sent Ghanaian intelligence operatives to be trained in Bulgaria, and other government officials have worked in Libya and Cuba, dissidents said.

Tsikata's intelligence and security forces are heavy-handed and have been involved in numerous violations of civil rights, according to dissidents and Henry Bretton, a professor at the State University of New York in Brockport, who is a Ghana specialist. "The country has been cowed more than ever," he said.

"The security force exists as much to keep the Ghanaians in line as anything else," and Tsikata in particular is feared by many Ghanaians, Ghana specialist Levine said.