"I had a deep relationship with the C.I.A.," he said in an interview, referring to his years as a senior official in intelligence activities in the 1950's and 1960's. "I went to their headquarters. But there was nobody in an authentic Government organization who received financial aid." He would not be more explicit.

"Those C.I.A. people who were stationed in the embassy with legitimate status were fine," he said. "But there were also covert people. We did not really know all the activities they were conducting. Because they were from a friendly nation, we did not investigate deeply." Recruitment Was 'Sophisticated'

The recruitment of Japanese conservatives in the 1950's and 1960's was "a pretty sophisticated business," said one C.I.A. officer. "Quite a number of our officers were in touch with the L.D.P. This was done on a seat-by-seat basis" in the Japanese parliament. A second C.I.A. officer said the agency's contacts had included members of the Japanese cabinet.

As the C.I.A. supported the Liberal Democrats, it undermined their opponents. It infiltrated the Japan Socialist Party, which it suspected was receiving secret financial support from Moscow, and placed agents in youth groups, student groups and labor groups, former C.I.A. officers said.

Obstructing the Japanese opposition "was the most important thing we could do," one said.

The covert aid apparently ended in the early 1970's, when growing frictions over trade began to strain relations between the United States and Japan, and the growing wealth of Japan made the agency question the point of supporting politicians.

"By that time, they were self-financing," a former senior intelligence official said. But the agency used its longstanding relationships to establish a more traditional espionage operation in Japan.

"We had penetrations of all the cabinet agencies," said a C.I.A. officer based in Tokyo in the late 1970's and early 1980's. He said the agency also recruited a close aide to a prime minister and had such good contacts in the agriculture ministry that it knew beforehand what Japan would say in trade talks. "We knew the fallback positions" in talks over beef and citrus imports, he said. "We knew when the Japanese delegation would walk out."