EAST BERLIN, FEB. 3 -- In a surge of protest, hundreds of East German citizens repeatedly have packed Protestant churches in East Berlin in the past two weeks to demand the release of a group of imprisoned human rights, peace and environmental activists.

The evening services begin with lengthy prayers and end with public discussions of the prisoners' cases. Participants frequently sing the American civil rights anthem "We Shall Overcome," in English.

Since police detained approximately 200 people who sought to stage an unauthorized demonstration on Jan. 17, crowds at the meetings have grown, in some cases to as large as 2,000.

The government, apparently caught by surprise by the size and persistence of the church meetings, has freed all but about 20 of the prisoners and sent about 60 of those released to West Germany. It has signaled that it will free the rest by the end of the week.

Nevertheless, the groundswell of dissent appears to mark a significant challenge to the communist leadership, according to western diplomats and other political analysts.

The events suggest that East Germany's younger generation is becoming reluctant to accept the government's severe restrictions on travel and freedom of expression, they said. Most of the detained activists and a large share of the protesters are middle-class people in their late teens to early thirties.

"There will have to be much more room for exchanging opinions than has been the case up to now," Manfred Stolpe, a senior church official, told more than 1,500 East Berliners at St. Bartholomew's Church on Monday.

East Germany's dissident movement is tiny compared to the one in Poland, but it has been growing in strength and bravado since the summer. An important contributing factor has been Soviet leader Mikhail Gorbachev's calls for more openness in communist societies, according to both dissidents and western observers.

The largest protests have been in East Berlin, but church officials said meetings have been held in 30 other East German cities and towns.

Here in the capital, the meetings are called at a different church each night. The meetings are held in churches because it is illegal to hold unauthorized assemblies anyplace else in East Germany.

The incident that sparked the protests occurred when a group of activists sought to join 200,000 people in a parade marking the anniversary of the murder in 1919 of German Communist Party founders Rosa Luxemburg and Karl Liebknecht. Some of the activists unfurled a banner bearing a quotation by Luxemburg: "Freedom is always only the freedom to dissent."

Most of those arrested sought to stage the demonstration with the aim of being detained in the hope of being expelled to West Germany, according to church officials and western diplomats. The East German government frequently has sent persons arrested on political charges to West Germany as a way of weakening the dissident movement.

About 60 of the detainees succeeded in their quest, as they were freed early last week and left with their families for West Germany. Since then, the protests have been staged on behalf of prisoners who wish to remain in East Germany and continue political activity.

At St. Sophia's Church this evening, 45 persons prayed "for those still detained" and for lawyer Wolfgang Schnur, who is defending them. The crowd was much smaller than usual because the service was only for prayers and did not include the political discussion afterward.

After each brief prayer, the congregation sang the Kyrie Eleison ("Lord, Have Mercy"), a refrain that has assumed political meaning here because of its use at the meetings.

Two of the best-known dissidents, ballad singer Stephan Krawczyk and his wife, theater director Freya Klier, were released yesterday and sent to West Germany.

They said today that the authorities had told them that they either had to leave East Germany or face prison sentences of up to 12 years for "treasonable contacts." Lawyer Schnur, however, said that they left willingly and that he was "incensed" by their statement because it could create difficulties for the activists still in prison.

Eleven of the prisoners have been convicted of "illegal assembly" and sentenced to six months in jail. But Wolfgang Vogel, a lawyer close to chief of state Erich Honecker, said yesterday that he expects all the prisoners to be freed by the weekend.