A U.S. Senate delegation led by John C. Danforth (R-Mo.) pressed Japanese Prime Minister Yasuhiro Nakasone this morning for more trade concessions, citing a continuing threat of legislation aimed at reducing Japanese imports.

In a meeting at his office, Nakasone pledged continued efforts to open the Japanese market to foreign goods and to reduce his country's trade surplus with the United States, which reached about $50 billion in 1985.

The meeting came one day after Secretary of State George P. Shultz and his Japanese counterpart Shintaro Abe broke a deadlock on forest products and agreed in Washington to expand trade negotiations to more industries.

Danforth said after the meeting here that both sides agreed that "the peace and stability of the world depend on a continuing strong relationship between the United States and Japan." Neither side was reported to have made specific proposals.

This visit was viewed as carrying special significance, because many Japanese view Danforth, who has promoted legislation considered here to be unfair protectionism, as a symbol of congressional hostility toward their country.

The meeting was described as cordial. Danforth told reporters later that he believed Nakasone was seriously trying to tackle the issue but that changes would not come easily.

According to Japanese accounts of the meeting, Danforth told Nakasone that Japan is inflicting serious damage on the world economy with its trade surplus and must start importing more. He said that steps taken by Japan so far were not sufficient and that negotiations should move away from focusing on specific products and aim at more general issues.

Nakasone cited the "action program" Japan has begun in a drive to increase imports and its efforts with the United States and other industrial countries to lower the value of the dollar.