There is growing evidence that the government of Vietnam has officially sanctioned the recent exodus of thousands of refugees who have landed in this country, according to Western diplomats and Malaysian authorities.

The manner in which the most recent refugees left Vietnam follows a pattern that must be officially approved at high levels, these sources contend.

"I am positive that the government is in on it," said one official who has interviewed thousands of refugees who landed here recently after crossing the South China Sea.

The officials base their judgment on the large fees paid to middlemen arranging the escapes and the easy manner in which large numbers of fleeing Vietnamese are passed through control points and provincial border crossings.

"The government is forcing out this undesirable minority,z" said one official. "They are escaping right under the eyes of the border police." It could not happen in such a regular way without the government approving of such large movements, he said. Many of the refugees from Vietnam are ethnic Chinese.

The Vietnamese government has repeatedly insisted that it is not encouraging the exodus, which has swollen to large proportions in recent months. It has claimed that it tries to stem the tide but is unable to patrol the country's long coastline.

The Vietnamese charge d'affaires in Malaysia, Tran De Luc, recently said his government is attempting to stop the flow. He told the Malaysian news agency Bernama that authorities had recently taken steps to reduce the number of escapes along the coastline.

The number arriving here has dwindled in the past week, but Malaysian authorities attribute that to rough seas in the monsoon season, not to deliberate action by Vietnam's government.

In October and November thousands of the refugees land on Malaysia's east coast and more than45,000 are still in coastal island camps awaiting resettlement in other countries.

They are being interviewed by Malaysian authorities and immigration officials of several Wester governments who have offered permanent resettlement to some.

Malaysian authorities have so far not officially accused Vietnam of abetting the escapes, although they have suggested in several interviews that the Communist country appeared not to be interfering with them. When Vietnamese Premier Pham Van Dong visited Malaysia several weeks ago he was asked to do something about the problem, but the large-scale escapes continued after his return home, the noted.

Those who came in the recent crossings tell stories different from those who had arrived by last summer as part of the slow migration that began soon after the fall of Saigon, now called Ho Chi Minh City, in 1975.

The early refugees came in small groups and told of gathering on Vietnam's coastline by their own devices until picked up at prearranged points by fishing boats. Some reported that their friends had been captured in the attempt and others recalled being fired on by coastal police.

The most recent arrivals, however, came in groups of several hundred on larger boats and about 2,500 arrived at one time on the freighter Hai Hong in November.

Western diplomats who interviewed them said their typical escape was arranged in Ho Chi Minh City by paying money to a middleman who agreed to get them to Malaysia. One source said the fees ranged anywhere from $600 to $3,500. They would gather at an agreed point in the city where they would be picked up in trucks and taken to coastal points.

Along the way, the trucks would pass through police control points where some of their money was handed over. The same would happen at provincial border posts and on the coast, according to the officials.

One Malaysian authority involved in the refugee problem ,Education Minister Datuk Musa Hitam, said the evidence is substantial that Vietnam is encouraging the departures in recent months. He cited reports of syndicates organizing mass escape parties.

"To get the large boasts they have and to get the people out to them the organizing syndicates must know that the government knows," Hitam said yesterday.

He cited the case of one recent arrival, a Malaysian who had brought out his Vietnamese wife. The Malaysian told authorities of having paid $2,000 to organizers, who collected a large number of people in trucks and passed easily through police checkpoints en route to the coast.

Among the latest refugees coming to Malaysia are a large number of ethnic chinese from the Cholon section of Ho Chi Minh City who were well-to-do businessmen and who decided they could not exist under a socialist regime after a government decree last March confiscated private property.

[At Kuala Trengganu, about 300 miles northeast of Kuala Lumpur, police turned away two boats carrying about 300 Vietnamese refugees who tried to land on the Maylysian coast, news services reported. They reportedly sailed for Pulau Bidong island, 25 miles offshore, where 24,000 refugees are in camps.]