The United States and Vietnam have resumed secret talks on normalizing relations, Acting Foreign Minister Nguyen Co. Thach said today.

Thack said the United States in June asked for resumption of negotiations that were suspended last fall.

The State Department denied Thursday that any new talks on normalizing relations were under way between the two countries. Richard Holbrooke, assistant secretary of state for East Asian and Pacific affairs, said, "I want to state that there have been no talks, secret or otherwise, on normalization of relations since last fall.

[Other State Department sources said two U.S. officials were being sent to Bangkok in hopes that they would be permitted to go on to Hanoi to assist a U.N. team that will be processing refugees.]

Thach refused at his news conference to say where the new discussions are going on, explaining, "I do not want to hurt the talks."

Thach's comments and other indications from Vietnamese officials during the 24-hour visit by a congressional delegation gave the impression that Vietnam is very eager to normalize relations. Nevertheless, they also indicated that they feel the initiative lies with the United States.

"The ball is now on the American side," Thach said.

An agreement on normalizing relations was very close in September, Thach told the group of reporters that accompanied the U.S. delegation.

"We had agreed to everything but signing papers," he said. The two countries even had established a working group to iron out details but, before it could accomplish anything, the United States said it was breaking off the talks, he said.

According to Thach, the American negotiators said that there were three obstacles to normalization: the presence of Vietnamese troops inside Cambodia; Vietnam's policy toward its own refugees, and the recently concluded Soviet-Vietnamese peace treaty.

"So it is crazy," he said. "At first the U.S. said there should be no conditions.So we dropped our conditions, and the U.S. has its own conditions. But we hope the mistake will end very soon."

The Vietnamese condition that Thach referred to was Hanoi's insistence that Washington supply several billion dollars in "war reparations."

Then-president Nixon, in the negotiations on the 1973 cease-fire agreement for South Vietnam, pledged aid to Hanoi. Following the Communist takeover of South Vietnam in 1975, U.S. officials said that the commitment no longer stood because of Hanoi's violations of the accord.

Thach indicated at the press conference that he thinks that the United States called off the normalization talks because it wanted to appease China. Last fall Washington was moving toward the establishment of full relations with Peking while the two Asian countries were becoming embroiled in a steady increasing quarrel, which was climaxed by China's brief invasion of Vietnam early this year.

Members of the House of Representative group, here for discussions about the Vietnamese refugee situation, said that they came away from their meetings with officials believing that Hanoi has a stong desire to establish ties with the United States.

Rep. Benjamin Rosenthal (D-N.Y.) said following a private session with Thach, "He is very anxious to normalize."

Rep. Lyle Williams (R-Ohio) said a Vietnamese official assigned to him was interested in talking about only normalization.

"I told him our side was not so interested in this a year ago," Williams said. He said, "Well, you make mistakes, you make mistakes.""

Another delegation from Congress, headed by Rep. Lester L. Wolff (D-N.Y.), chairman of the House subcommittee on Asian and Pacific Affairs, is to arrive here Friday. Wolff has said that his group hopes to discuss the normalization question.

[In his statement denying that there had been any resumption of talks on formal relations with Hanoi, Holbrooke said, "Vietnam's actions towards its own people, resulting in a flood of refugees, have made it impossible for us to continue with normalization. We have made this position clear both publicly and to Vietnamese officials.]