Two months after South Korean opposition leader Kim Dae Jung was abducted in Tokyo the Japanese government was advised that the Korean Central Intelligence Agency had played a role in the kidnaping, the Japanese Foreign Minister said today.

The disclosure contradicted the government's long-standing claim that is has had no evidence that the KCIA was involved in the affair and has added new pressure on the government to reopen the controversial case.

The Foreign Ministry confirmed the details of a Mainichi newspaper story based on a secret document naming two officials as the most likely planners of the kidnaping.

A spokesman for the ministry said the document had been written by a private individual retained to look into the case and represented only his personal opinion, not the considered view of the government.

Nevertheless, opposition leaders in Japan's parliament used the revelation to press Prime Minister Masayoshi Ohira to reopen the case. He refsed to commit his administration, but said the Foreign Ministry is still trying to collect information on the abduction.

Kim Dae Jung, South Korea's most celebrated opponent of President Park Chung Hee, was kidnaped from a Tokyo hotel in August 1973 and forcibly returned to Seoul by ship. He was arrested in 1976 for criticizing Park's government and served 2 1/2 years in prison before being released last Dec. 27 in a presidential amnesty. He has asserted that the KCIA was involved in his kidnaping but has never presented any evidence of it.

In November 1973, Japan and South Korea reached what was called a "political settlement" of the case, which had the effect of ending Japan's official interest. The government, however, has repeatedly been accused of permitting Japan's sovereignty to be abused and of failing to pursue the truth because it might disrupt the two countries' close relationship.

It is a potentially embarrasing issue for Ohira, who was foreign minister at the time of the abduction. He acknowledged having read the report divulged by Mainichi papers when it was prepared in 1973 but said it was only one bit of information available at the time.

In recent days, Ohira's government has given a small hint that it might be changing its mind. It has authorized its ambassador in Seoul to meet with Kim Dae Jung, who had asked for a meeting to discuss details of the kidnaping.

Today's disclosure was the second revelation in the past month of possible KCIA involvement. Kyodo News Service reported in May in a story from Washington that confidential State Department documents gave indications of a KCIA role.

It quoted a 1975 cable from then U.S. ambassador to Seoul, Richard Sneider, who said he was told by former foreign minister Kim Dong Jo that a KCIA agent "responsible for the Kim Dae Jung kidnaping" would be "quietly dismissed" from the agency, apparently to pacify the Japanese goovernment.

That agent was identified as Kim Dong Un., who at the time of the abduction was listed as first secretary at the South Korean embassy in Tokyo.

The South Korean government has acknowledged Kim Dong Un's dismissal but denied there is any evidence he took part in an abduction.

The document that surfaced here today was written by a "non-government expert on Korea," according to a Foreign Ministry spokesman, who declined to disclose his identity. His report, which was submitted in October 1973, was based on interviews in Seoul.

It said there is "almost no doubt" that two officials - Park Chong Rak and Lee Hu Park - were responsible for planning the kidnaping. Park was then head of President Park's personal security force and Lee was then director of the KCIA.

The author concluded it was unlikely that President Park personally ordered the kidnaping but that the two men may have given the orders as being "the wish of the president."

It said the South Korean government was bent on a defense of claiming the kidnaping was an "international conspiracy" and was determined to prevent an investigation from reaching upper-level officials.

It also said that except for President Park's most devoted loyalists Korean people believed the kidnaping was the work of the KCIA.

The document went on to propose that Japan's policy should be to "respect the honor" of President Park and to avoid weakening his government because that might have an important political and economic impact on Japan. It said a political compromise which avoided tracing blame to high Korean officals should be worked out. CAPTION: Picture, KIM DAE JUNG . . . Korean opposition leader