The Soviet Union, a year after the fact, has announced a ''governmental agreement'' bringing thousands of Vietnamese civilians to this country for ''training and work.''
The Vietnamese, according to the Soviet report, are to stay for periods of ''up to five years'' - the first year for language and labor training, and the remainder on the job.
The Soviets' April 30 disclosure of the accord followed foreign reports that Vietnam, in economic crisis, was exporting labor to help dent its enormous state debt to the Soviet Union. The reports suggested that Vietnamese workers could also help the Soviet Union ease a shortage of domestic labor in some sectors of the economy.
Moscow's version does not explicitly refute any of this, but portrays the Soviets in the role of selfless benefactors, helping train Vietnamese and taking scrupulously good care of them while they are here.
(A second Soviet mention of the agreement, on the evening of May 3 in the government newspaper Izvestia, went further, branding as ''slander'' Western reports that the accord was part of Vietnamese debt payment. Izvestia did not address suggestions that the Vietnamese workers might be meant to help alleviate shortages of Soviet labor.)
The initial Soviet statement came in the form of a lengthy dispatch from the official news agency Tass, marking the first ''anniversary'' of an agreement not previously publicized. The accord is termed a ''new form of cooperation in the sphere of training skilled cadres for the Socialist Republic of Vietnam.'' In the past year, 7,000 Vietnamese are said to have arrived here under the terms of the agreement.
''In accordance with the wishes'' of the Vietnamese government, the Soviet account says, most of the Vietnamese are sent to ''machine building enterprises, the chemical and textile industries, (and) projects of irrigation and land reclamation.''
The Soviet report seems aimed partly at dispelling the image created by some foreign reports of difficult working conditions for the Vietnamese.
Countering suggestions that many of the Vietnamese are doing battle with the wilds of Siberia, Tass says: ''Taking into consideration the Vietnamese climate, young people from Vietnam are sent mainly to southern districts of the European part of the USSR.''
The Tass dispatch quotes a Soviet official as saying the Vietnamese get the same pay and benefits as Soviet workers, and even ''vouchers for rest homes, . . . free medical care, and state social insurance benefits.''
According to the foreign news reports, part of the Vietnamese workers' earnings is being credited against Vietnam's debt to Moscow. The Tass report does not tackle this issue directly. It says that the ''Vietnamese citizens, at their discretion, can remit part of their earnings for their families at home.''
Estimates of the Vietnamese debt to Moscow vary. But official figures for what amounts to one form of Soviet subsidy for Vietnam's troubled economy--the states' trade relationship--show a Vietnamese deficit for 1981 of some 560 million rubles. At official hard-currency exchange rates, this would equal about
A US congressional report esimates that 1981 Soviet hard-currency subsidies to Vietnam totaled slightly more than $1 billion.
Given the scale of subsidy involved, the presence of 7,000 Vietnamese workers here could involve, at most, a token repayment, in the view of diplomats.
The Soviets tend to avoid any public suggestion of displeasure at the size of transfers made to states like Vietnam, Laos, or Cuba. Yet one hint of possible Soviet uneasiness came when President Brezhnev coupled a recent pledge of further aid to Laos with a call for more timely and extensive implementation of existing aid projects.