Vietnam will consider letting U.S. planes land in that nation to pick up refugees trying to leave, Acting Foreign Minister Nguyen Co Thach said today.

In a freewheeling session with American reporters covering the second visit of U.S. congressmen to Hanoi in less than a week, Thach also said the exodus of thousands of Vietnamese in recent months has had a severe impact on the Vietnamese economy and that Hanoi has no immediate plans to withdraw troops from Cambodia.

Thach's comments were the first suggestion from a ranking Vietnamese official that Hanoi would consider direct American flights for the purpose of evacuating refugees. Although he said the government was willing to discuss the possibility, he stressed that he could make no promises.

[State Department sources said last night that the United States probably would look at the possibility of evacuation flights to Vietnam if Hanoi allows sufficient numbers of refugees to leave under a family reunification program.]

Yesterday, State Department sources said two U.S. officials were being sent to Bangkok in hopes that they would be allowed to assist a U.N. team that will be processing refugees in Hanoi.

Thach said today that Hanoi was taking drastic steps to stop the flow of refugees from Vietnam and cited the arrest of 4,000 persons who organized escapes. Vietname pledged to cut the flow of refugees in mid-July at a U.N.-sponsored conference in Geneva.

The acting foreign minister, an influential figure in the Communist Party hierarchy, said the impact of the large-scale exodus on the economy was "very great" because of the loss of technicians, doctors and managers.

"So we suffer from this exodus," Thach said. "The Chinese were good managers." The overwhelming majority of the Vietnamese refugees have been ethnic Chinese.

Thach said that industrial production has been slowed by the loss of skilled workers and that even Vietnam's important fishing industry has suffered because of the many boats by the refugees fleeing to neighboring countries via the South China Sea. Independent sources here confirm this.

The fishing industry has been cut in half, Thach asserted, because refugees took 5,000 fishing boats. Thach painted a generally gloomy picture of a Vietnamese economy in considerable trouble and cited a growing food shortage as one example.

Hanoi is expecting a big shortage of rice this year and Thach said even his personal ration of the staple has been reduced.

Vietnam has sought, as part of its attempt to normalize relations with the United States, several billion dollars in "war reparations" from the United States.

Yesterday Thach said the United States and Vietnam had resumed secret discussions aimed at normalization of relations, but the State Department denied his claim. Officials since have said that the two countires were near agreement in September, but the accord was shelved when Vietnam started expelling ethnic Chinese residents and invaded Cambodia.

Thach said today that Vietnam will not withdraw from its remaining troops in Cambodia until there is no more threat to Vietnam or Cambodia from China. He said Hanoi rejects the idea of an international conference to solve the Cambodian problem.

Earlier today, a 10-member congressional delegation headed by Rep. Lester Wolff (D-N.Y.) arrived in Hanoi to discuss the normalization issue and refugee problems.

The Wolff mission is also expected to ask Vietnamese leaders about unaccounted for Americans missing in action from the Vietnam war. The group is scheduled to meet Premier Pham Van Dong Saturday afternoon.

Another group of congressmen led by Benjamin Rosenthal (D-N.Y.) left Hanoi Thursday after talks with Vietnamese leaders.