Vietnam said today that a delegation of U.S. congressmen scheduled to visit Hanoi Wednesday is no longer welcome because of critical remarks made by one member of the group.

Hanoi Radio accused Rep. Robert Drinan (D-Mass.) of having made "slanderous" statements about Vietnam last week.

The radio, monitored in Bangkok, was quoting from a statement issued by the Vietnamese Foreign Ministry.

"Vietnam is not ready to receive the delegation," the statement said.

Although the wording of the broadcast account did not say the delegation would actually be barred from Hanoi, a spokesman for the Vietnamese embassy in Kuala Lumpur, Malaysia, later said the invitation for the entire nine-member group had been withdrawn.

Vietnam has informed the U.S. government that the delegation is not welcome, according to U.S. embassy sources in Kuala Lumpur quoted by Associated Press.

Members of the congressional delegation, which is headed by Rep. Benjamin Rosenthal (D-N.Y.), were scheduled to enter Hanoi Wednesday afternoon after an overnight stopover in Malaysia. The delegation is on a six-day tour of Southeast Asia to investigate problems of Indochinese refugees.

Rosenthal said this morning he hoped the delegation is still able to visit Hanoi. He said he had no idea what the Vietnamese expected the delegation to do in order to make the trip.

Drinan, the center of the controversy, said at a news conference, "I'm sorry that they may have misunderstood something that one member of the delegation said."

Asked if he thought his comments might be considered inflammatory, Drinan said, "Obviously Hanoi sees what they are doing in a different light from the rest of the world."

It was not immediately clear which of Drinan's statements the Hanoi radio broadcast referred to. At a news conference in Hong Kong last Saturday, he had denounced the "new economic zones" in Vietnam where former city dwellers are expected to start new lives learning to grow crops in the countryside.

Drinan called them "the new gulags" and "concentration camps" and said Vietnam was guilty of a fundamental violation of human rights.

However, Hanoi radio said Drinan had "slandered" Vietnam on the subject of family reunifications. This apparently referred to a continuing dispute between Vietnam and the United States over the issue of bringing certain refugees to the United States to join families already living there.

The radio broadcast asserted that Drinan's statement "made it clear that the United States does not wish to cooperate" on the family reunification issue.

The congressional delegation flew to Jakarta after conferring with Tahi Prime Minister Kriangsak Chamanand in Bangkok.

Kriangsak told the delegation that the refugees problem will grow worse this fall because an expected famine in Cambodia will force many hungry people to try to flee to Thailand.

The Thai premier said a rice shortage will become critical in about two months, according to the congressmen. He estimated that even now only 5 or 6 percent of the Cambodians are able to support themselves by growing their own food.

Kriangsak also said that the refugee problem in his country will not be improved significantly until Vietnamese forces withdraw from Cambodia.

Refugee officials have been expecting a famine to strike Cambodia this fall because few farmers have been able to grow rice since fighting began last December. At that time Vietnamese troops led Cambodian allies in an invasion that toppled the government of Pol Pot.

Vietnamese forces have occupied most of the country and have installed a new government in Phnom Penh. They continue attempts to mop up remnants of the Pol Pot forces.

According to Rosenthal, who briefed reporters after the meeting, Kriangsak said the only solution that would halt the flow of refugees would be a withdrawal of Vietnamese forces to permit the Cambodians to choose their own government. Rosenthal said the prime minister offered no ideas on how this might be brought about.

U.S. officials here have expressed fears that a famine-propelled exodus of Cambodians into Thailand this fall could trigger a wholesale campaign by the Thais to force thousands of other refugees back to their home countries, regardless of the consequences.

More than 175,000 Cambodian, Laotian and Vietnamese refugees already are in camps in Thailand. Last June, the Thai military forced more than 40,000 Cambodians to reenter the country they had fled and their fate is still not known here.

There are also widespread reports in Bangkok that the Thais may soon force thousands of Laotians to leave camps and return to their country, where they would face hostile forces. A Thai government delegation is scheduled to discuss what is called "repatriation" with Laotian officials next week in Vientiane.

The U.S. congressmen raised questions about that possibility this morning with Air Marshal Sitthi Sawetsila, chairman of the Thai National Security Council and Thailand's top official on refugee matters. They said later he gave assurances the Thais have no plans to pressure the Laotian refugees to return home, but acknowledged that repatriation will be discussed.

Rosenthal said the congressmen also questioned Kriangsak about measures the government is taking to stop the Thai fishermen from assaulting Vietnamese refugees fleeing in small boats. Numerous reports have been made of Thais boarding vessels to rob refugees of gold and rape the women passengers. Recently there have been more accounts of Thai fishermen murdering refugees at sea.

Rosenthal said he told Kriangsak the piracy was an "unacceptable situation." Kriangsak replied, Rosenthal said, that the coastline is too long for Thai patrols to stop the piracy.

The prime minister was also asked why Thai guards last week prevented nearly 200 fleeing Laotians from coming across the Mekong River. The Laotians had been caught on an island in the middle of the river and all of them were killed or captured by pursuing Laotian government soldiers.

The congressmen quoted Kriangsak as saying the Thai guards were following an "old" policy of preventing refugees from entering the country. He indicated there would be a relaxation of that policy but gave no details, the congressmen said.

Rosenthal said the prime minister expressed concern that refugee organizations and officials including the United Nations high commissioner for refugees, had become too concerned about the Vietnamese who flee by boats and not sufficiently aware of the thousands of others who came overland to Thailand from Cambodia and Laos.

The congressmen visited several refugee camps in Thailand yesterday, and Rosenthal said he found conditions in the one he toured worse than he had expected.

He said there were problems with food distribution and medical care.

"The medical situation especially needs emergency attention," he said. were bloodied in the fighting outside the Waterside Workers' Federation.

Police said four Vietnamese and five Australians were arrested.

The protesting refugees arrived at the headquarters of the federation and tried to drag the two Vietnamese trade unionists from their car.

Dockworkers rushed from the federation hall, pushing and shoving the protesters back to clear a path for Nguyen Thuyet, general secretary of the Vietnam Trade Union Federation, and Do Tong Hop, an official in the union's international department.

At least six screaming Vietnamese wielding sticks ran across the street and began hitting the dockworkers, who chanted "Ho, Ho, Ho Chi Minh," police said.