About 20 people were feared dead on Thursday after protesters battled police and soldiers in several towns of Bas-Congo Province, in western Democratic Republic of Congo, witnesses said.

"Four policemen and one army officer were among those killed in Moanda," Honoré Kapuku, interim president of the local agency Voix de Sans Voix (Voice of the Voiceless), said.

On state-owned radio, Mayor Marc Nzeyidio Lukombo of Matadi, the provincial capital, announced three deaths. Dozens of corpses were retrieved and taken to the Matadi General Hospital mortuary. A police commander in Matadi said six people were killed in the town of Moanda and three in Boma.

Police and army officers, who spoke on condition of anonymity, said supporters of the Bundu Dia Kongo (meaning the Kongo Kingdom in the local Kikongo language) had attacked a police and army post and killed four policemen and an army major.

The Ministry of the Interior and many other security officials did not comment on the demonstrations because they were in Bas-Congo for an urgent security meeting.

A resident of Lukunga town, Nyebere Pambo, said the demonstration there turned violent when thousands of protesters "provoked police and soldiers who tried to disperse them". However, the Bundu Dia Kongo leader, Semi Mwanda, said their "peaceful demonstration was put down harshly by police and the army".

Radio Okapi, supported by the United Nations, said the demonstrations took place in several localities of the province, among them the towns of Matadi, Moanda, Boma, Kasangulu and Kinzaomvwete. Businesses closed and traffic was halted when demonstrators set up barricades.

Supporters of Bundu Dia Kongo, a politico-religious body supporting failed presidential candidate Jean-Pierre Bemba, were protesting against senatorial and gubernatorial elections held last week and the week before, respectively. In the senatorial elections, the party of President Joseph Kabila won 80 percent of the seats.

Bundu Dia Kongo allied with the party of Kabila's presidential rival, the Mouvement pour la libération du Congo, during the second-round presidential elections in December 2006.