HAVANA - (AP) -- Dressed in black and white to express both mourning and peace, about 30 women gathered at a Roman Catholic church Sunday to pray for the release of their imprisoned dissident relatives.

The women attended the Mother's Day Mass at the Church of St. Rita, the patron of lost causes, four weeks after their loved ones were sentenced to prison terms ranging from six to 28 years.

''The best gift we could get on this day is their freedom,'' said Gisela Delgado, wife of opposition party leader Héctor Palacios, who was sentenced to 25 years.

Palacios was among 75 government opponents arrested in March and tried in April.

Fidel Castro's government accused them of accepting payment from the United States government to engage in subversive activities, something the dissidents and U.S. diplomats deny.

The nongovernmental Cuban Commission of Human Rights and National Reconciliation estimates there are about 300 prisoners of conscience on the island, including those tried in the recent crackdown.

The wives and mothers of those arrested in the recent wave said Cuban authorities prohibited them from marching in silence for two blocks near the church, as they've done on past Sundays.

''They thought it would be a provocative act,'' Delgado said. ``They were prepared to arrest us.''

Miriam Leiva, wife of independent journalist Oscar Espinosa Chepe, said state security agents had visited her and other relatives to warn them against marching.

In a letter handed to international reporters, Leiva also pleaded with the United States not to take serious action against Cuba, saying she feared that the communist government would retaliate ``against the weakest and most defenseless.''

The Bush administration is contemplating action against Cuba in response to the recent crackdown, though it has denied plans for a military attack.