The United States has asked the Nicaraguan rebel leadership to help locate eight West German citizens reportedly captured by U.S.-backed rebel forces in southern Nicaragua over the weekend, the State Department said yesterday.

A spokesman said the United States is "assisting West German authorities to ascertain the welfare and whereabouts" of the Germans. The four men and four women were captured Saturday in a village named Joaquin Baca, where they were helping to build housing for war refugees, according to four of their companions who escaped the rebel attack.

The State Department spokesman said representatives of the United Nicaraguan Opposition, a federation of the main rebel groups, had been "made aware of our concerns and asked for assistance in locating the West German citizens."

The capture of the West Germans, who were unarmed civilians, raised anew questions about human rights abuses by the rebels, known as counterrevolutionaries or contras, as Congress debated an administration proposal to provide them with $100 million in aid, much of it military.

"It's just another example of the problems we have with the group the government is supporting down there," said Richard L. McCall, an aide to Sen. John F. Kerry (D-Mass.), who opposes the aid.

In Tegucigalpa, the capital of "They are no more than a bunch of Communist internationalists." -- contra spokesman Honduras, a spokesman for the largest rebel group, the Nicaraguan Democratic Force, told Reuter that the Germans were being held by a contra patrol that was pinned down by fire from Nicaraguan government forces.

Spokesman Frank Arana said the Nicaraguan Democratic Force was willing to release the eight Germans as soon as the patrol could break free of the combat.

"The Sandinistas are trying to hurt the prisoners and make it look like it was our fault," Arana said.

In Managua, however, a Nicaraguan Defense Ministry spokeswoman quoted Roberto Calderon, the military chief of the region where the Germans were captured, as saying the rebels were being pursued but that troops were maintaining their distance so as not to endanger the lives of the Germans.

The West German captives were among the hundreds of North American, Latin American and European volunteers who come to Nicaragua to assist the Sandinista government. Many work in the fields during the harvests while others are teachers or medical workers.

In Tegucigalpa, Arana had denounced the German volunteers, saying: "For us, whether they are East or West Germans, or whatever nationality, they are no more than a bunch of Communist internationalists who have come to occupy our country and impose a totalitarian regime in Nicaragua," Reuter reported.

In Managua, 70 West Germans who had occupied their country's embassy to draw attention to the capture of the eight volunteers ended their demonstration.