Two months after he disappeared from his job at American-run Radio Liberty in Munich, Soviet-born Oleg Tumanov appeared in Moscow today to say his 20 years in the West had been a "nightmare."

But at a news conference today, Tumanov, 42, whose last job was editor of the Russian service at Radio Liberty, gave no details on how or when he made his way back east, and gave no full explanation of why he chose to return.

"I am here and I am home," said Tumanov, who was assisted at the press conference by a representative of the Soviet Foreign Ministry and legal experts.

Tumanov, in a prepared statement, accused Radio Liberty, which directs broadcasts to the Soviet Union, and Radio Free Europe, which is broadcast to Eastern Europe, of being under the control of the Central Intelligence Agency. The stations, funded by the U.S. government, are jammed by Soviet authorities.

"Radio Liberty and Radio Free Europe are a branch of the U.S. secret services, a convenient front for covert operations against the U.S.S.R. and other socialist countries," he said. Tumanov named directors at the station as being members of either the CIA or U.S. military intelligence.

Tumanov refused to answer why he had stayed 20 years in the employ of Radio Liberty. He was a 21-year-old seaman in 1965 when he jumped ship off the coast of Libya. Today he called his defection a product of "youth's illusions."

He came back, he said, because "at a difficult time, and the world's going through a difficult time now, every honest person should be with his own people." He refused to elaborate.

In his statement today, Tumanov also accused several Moscow-based correspondents of helping Radio Liberty gather information from underground publications or dissident circles.

"The radio service's 'assets' also include some foreign correspondents accredited in Moscow," he said.

When pressed later, Tumanov named Tim Sebastian, a BBC correspondent expelled from Moscow last fall, a former Baltimore Sun correspondent and Serge Schmemann of the New York Times.

In giving details, Tumanov appeared to back off from the claim that these journalists worked for or helped Radio Liberty. He noted, for instance, only that Schmemann used their research service, as do many other western reporters.

The inference about Moscow-based western journalists came on the heels of an article in Saturday's editions of Sovietskaya Rossiya attacking the correspondent for the Philadelphia Inquirer, Donald Kimelman. The article also insinuated links between the CIA and American journalists.

The article, considered by veteran correspondents as a particularly distorted and vicious personal attack on an accredited correspondent, was brought up at today's press conference, contributing to an unusually tense atmosphere.

Referring to the Saturday article, a spokesman for the Soviet Foreign Ministry said "no western journalist has been smeared by calumny" in the Soviet press.