Stockholm — Soviet Latvia is experiencing the worst wave of political repression in recent memory, according to exile Latvian sources. Two Latvians were sentenced on political charges in August, and autumn may see the trial of four more religious and political activists. This is the largest known number of trials since eight persons, most of them intellectuals, were sentenced to long prison terms for alleged nationalist conspiracies in the early 1960s.
Gederts Melngailis, a former Lutheran seminary student, was sentenced to three years in a prison camp, Latvian exile sources reported Tuesday. The charges against him apparently stemmed from attempts to renounce Soviet citizenship, his refusal to serve in the Soviet Army, and contacts with Westerners in Moscow and Latvians in the West.
Before he serves his prison terms, Melngailis will undergo psychiatric treatment. Saying it would bring a milder sentence, his defense lawyer persuaded his mother to sign a statement that her son was mentally ill. ''All experience with other dissidents shows that this is the worst that could possibly happen,'' commented Julijs Kadelis, head of the Information Bureau of the World Federation of Free Latvians in Munster, West Germany. Kadelis, who runs a clearinghouse for information on dissent in Latvia, said police and KGB officials had earlier threatened to ''change'' Melngailis's way of thinking with drug treatment at a mental hospital.
Exile sources in Stockholm said a Sept. 15 trial date has been set for Ints Calitis, who signed appeals for a nuclear free zone in the Baltic states and supported a protest by Balts on the 40th anniversary of the Molotov-Ribbentrop pact of 1939. Secret provisions of the treaty between Stalin's Russia and Hitler's Germany assigned the Baltic states to the Soviet sphere of influence.
A Soviet Latvian court recently sentenced Lidija Lasmamis-Doronina to five years in prison and three years exile, her third stint in a Soviet prison since 1948. She is a Baptist accused of possessing writings from the unofficial Soviet peace movement.
Soviet authorities have also indicated to relatives that they will try Janis Rozkalns, a Baptist, sometime in late September. He was arrested in April and charged with anti-Soviet activity for having quantities of religious literature and copies of the UN Universal Declaration of Human Rights in his home. He may be tried with Janis Rozkalns, and Janis Veveris, a former champion rower arrested in early January.
When the trials of Rozkalns, Calitis, and Ververis end, Kadelis in Munster says it will probably be Gunars Freimanis's turn. The electrician was arrested in late March, apparently for reading and circulating his uncensored poems to friends. He was imprisoned from 1964 to 1969 on similar charges, although a few of his poems on environmental issues appeared in the official Soviet-Latvian literary magazine Karogs in the early 1960s.
The trials are seen as part of an ideological crackdown under Yuri Andropov aimed at the most Western-oriented republics in the Soviet Union. ''When the head of the KGB becomes the head of the USSR, it is clear that he wants to put the house in order,'' said Atis Lejins, a Latvian-born American citizen who edits a journal for the exiled Latvian Social Democratic Party in Stockholm. He also links the crackdown to the campaign for economic and workplace discipline.
Kadelis thinks the crackdown may reflect a need by officials in Latvia to show their power and loyalty to the new men in the Kremlin. ''What has happened is the whole KGB apparatus has awakened and is doing things to gain attention and favor now that the former KGB chief has become the top man in the Soviet Union,'' he says.
Lejins suggests the repression may backfire by putting the Soviet Union in an embarrassing position concerning its promises to respect human rights at the Madrid conference to review the 1975 Helsinki Accords.
From its outset in January, the Latvian crackdown has been an international incident. When Doronina was arrested in January, KGB agents also seized a Latvian-born woman and her teen-age daughter, both Swedish citizens in Latvia as tourists. The incident was widely publicized in Sweden and is often mentioned in reports of the current trials. Both women were expelled from the Soviet Union.