Slowly and grudgingly, the South Korean government is giving some ground in the tug of war with Washington over Tongsun Park but no one is willing to say how much.

Competent sources describe the government as shaken by the new threat of losing U.S. military assistance if it prevents Park from giving testimony in the congressional lobbying scandal.

As a result, the sources said, the government is shifting from its adamant refusal to make Park available for questioning.

Neither South Korean nor U.S. officials would divulge details of Foreign Minister Park Tong Chin's new offer, made Monday in a conversation with U.S. Ambassador Richard L. Sneider.

Sneider is scheduled to meet again this week with the foreign minister as soon as the State Department has examined the package of proposals, some of which are said to have been considered previously in bargaining sessions between the two governments.

The Korean press speculated that the government offered to make Tongsun Park available for interrogation in a neutral third country after a preliminary questioning by U.S. officials in Seoul. On Monday the Hapdong news agency said the foreign minister had made such an offer at his meeting with Sneider.

A similar proposal made here two weeks ago by Assistant U.S. Attorney General Benjamin Civiletti was rejected by South Korean officials.

The new willingness to compromise is a substantial change from the attitude that prevailed a month ago, when the government insisted Park was a free citizen whose civil rights would be violated if he were forced to testify.

Shortly after Civiletti left Seoul, the government began to signal a change. Newspapers were advised that negotiations had not irrevocably collapsed but might continue through diplomatic channels.

What finally prompted the new offer, observers said, was a statement by Rep. Clement Zablocki (D-Wis.), chairman of the House International Relations Committee, about the proposed transfer of U.S. military equipment to South Korean forces when American troops are withdrawn over the next four to five years.

Zablocki said the transfer plan could not win congressional approval so long as Seoul refused to cooperate with the investigation.

In the opinion of one diplomat, Zablocki's comment convinced the government that something had to be done.

Of lesser importance, apparently, was the House vote Monday calling on South Korea to "cooperate fully and without reservation" in the inquiry. News stories quoted Foreign Ministry sources as saying the resolution merely expressed a point of view and had no binding effect.

The threatened loss of military equipment has touched an exposed nerve. Echoing the government's position, a number of newspaper editorials today vehemently objected to any linking of the Tongsun Park case to the question of U.S. military support for South Korea.

One prominent editor, in a lengthy essay, charged that withholding military equipment amounted to toying with the lives of 35 million South Koreans threatened by the north.

"There is only one instance in which the U.S. rejection of compensatory measures for the troop withdrawal can be justified," wrote So Nu Whi in the Chosun Ilbo. "It is when it does not care if Korea falls prey to Communist North Korea."