Police arrested 21 members of a banned peace group who met in a Warsaw apartment Saturday, a spokesman for the group said. Jacek Czaputowicz, leader of Freedom and Peace, said there had been no attempt to keep the meeting a secret. It was the first time police detained members of the group at such a session, he said. The meeting was of the group's national board in charge of raising money, paying legal fines and providing financial assistance for imprisoned activists, he said. A municipal official arrived with police at the apartment at about 11 a.m. and declared the meeting illegal, Czaputowicz said. Police detained everyone present, and 17 people remained in custody Saturday night, he said. Opposition activists in Poland frequently are detained for up to 48 hours on misdemeanor charges. Freedom and Peace opposes Poland's military draft and demands the right to alternative civilian service. It continues to operate even though it has been declared illegal. On Friday, Poland's National Defense Ministry Council endorsed government proposals announced earlier to permit ``alternative forms of military service.'' Czaputowicz said the detentions may be intended to show that alternative service, if it eventually becomes law, did not result from pressure from Freedom and Peace.