Dozens of people have been injured in clashes between supporters of competing political parties in Zambia since parliamentary by-elections this week, Reuters quoted police as saying on Saturday. Home affairs minister Lameck Mangani described the clashes between supporters of the ruling MMD party and the opposition as the worst violence during an election since Zambia's independence from Britain in 1964. Police have arrested 24 people since the violence erupted in Northwestern province on Thursday during the by-elections, in a sign of mounting tension ahead of 2011 presidential and parliamentary polls in Africa's largest copper producer. Police said supporters of the two camps clashed using knives and stones. The opposition has accused President Rupiah Banda's MMD party of fanning the violence. In turn, the president has blamed the opposition for the clashes on by-election day. Police spokesman Moses Suwali said one policeman was battling for his life after being abducted and battered by those believed to be opposition supporters. "It is regrettable that political parties are now resorting to violence in an attempt to win elections at all costs," Banda's spokesman, Dickson Jere, said in a statement. In polls held on Thursday, the MMD lost one of two parliamentary seats to the opposition alliance comprising the Patriotic Front (PF) and third largest party in parliament, the United Party for National Development (UPND). The MMD retained a seat in its stronghold eastern province. Main opposition PF leader Michael Sata and UPND leader Hakainde Hichilema forged an alliance seen by analysts as the first real challenge to Banda, since the MMD came to power in 1991. The alliance has won three seats in by-elections after the deaths of legislators since mid-2009 in MMD strongholds. -- SPA