An opposition activist has been shot dead in Democratic Republic of Congo during clashes with police in Kinshasa.The fighting came after the offices of the opposition Union for Democracy and Social Progress were set alight, and an opposition TV station was attacked.UDPS activists said police had opened fire with live ammunition. The police have not yet commented on the claims.UDPS candidate Etienne Tshisekedi is the main challenger to President Joseph Kabila in an election set for November.Some of the gang that attacked the UDPS offices wore T-shirts of Mr Kabila's People's Party for Reconstruction and Democracy (PPRD), a witness told Reuters news agency.DR Congo's Interior Minister Adolphe Lumanu Mulenda told a news conference the attacks may have been retribution for a similar attack on a PPRD building on Monday."Probably reacting to the attack on the inter-federal seat of the PPRD, some troublemakers have sacked the offices of the UDPS and RLTV television channel," he said.Several people have been injured in various clashes over the past few days, says the BBC's Thomas Hubert in Kinshasa, adding that the capital remains tense.