The American ambassador to South Korea is scheduled to see Sen. Adlai Stevenson (D-Ill.) this morning for a discussion that illustrates a continuing confrontation between the executive branch and Congress over aid to Korea.

Stevenson said yesterday that he expected to talk with Ambassador Richard Sneider about his intention to block a $500 million Export-Import Bank loan to Korea unless the Seoul government cooperates more fully in investigations of alleged Korean influence-buying in Congress.

Accused Korean agent Tongsun Park is on his way back to Washington for secret questioning by congressional investigators set to start next Tuesday.

And the Carter administration has sided with the Korean government in resisting congressional requests for access to Korean diplomats implicated in the affair.

But Stevenson, chairman of the Senate ethics committee, and Leon Jaworski, head of the counterpart House investigation, have said repeatedly that they need the information of figures such as Kim Dong Jo, the former Korean ambassador to the United States. And they have dismissed administration arguments that it is unfair to tie continued U.S. aid to such cooperation.

Rep. Clement J. Zablocki (D-Wis.), chairman of the House International Relations Committee, for instance, told Defense Secretary Harold Brown on Wednesday that he didn't think the House would approve transfer of $800 million in military equipment to the Koreans because of the influence-buying scandal.

Stevenson said in a telephone interview yesterday that "I don't think it's wise to cut off military aid because of the national security implications for both countries."

"But I'm not sure the State Department fully understands the Ex-Im Bank exposure in Korea," he said.

Stevenson is head of the Senate Banking subcommittee on international finance and said he would not consider a loan for the Koreans two nuclear reactors from Westinghouse Electric Co. until the Koreans agree to cooperate.

"Unfortunately, Tongsun Park's testimony is not enough," he said. "We do need, if not the testimony, at least communications with other Korean nationals, to do a credible job of investigating." House investigators have taken the same position.

One senior administration official said yesterday that the United States would lose needed export business to foreign competitors if loans such as that for the Westinghouse reactors are blocked.

Stevenson said: "Westinghouse can be sacrificed, if necessary, for the integrity of the Congress."