JUBA, Sudan (Reuters) - At least seven civilians were killed in crossfire as cattle-herding tribesmen attacked a weapons store to try to get arms to retaliate against a rival clan who had attacked them, officials said on Sunday. Sudans south has been hit by a wave of ethnic violence that has killed at least 2,500 people since the beginning of last year, aid groups say, threatening stability in the oil-producing region ahead of presidential and legislative elections due in April. Violent cattle rustling raids are common in the underdeveloped territory, but the scale of the recent carnage has sparked accusations of political meddling. Members of the Rek Dinka ethnic group attacked a camp occupied by Gok Dinka cattle herders in the remote Bahr Gel area of south Sudans Lakes State on Saturday, southern army spokesman Kuol Diem Kuol told Reuters. A Gok Dinka group then went to the nearby settlement of Cueibert and tried to break into an army weapons store, filled with guns taken during a recent state-wide disarmament exercise, he said. The guards guarding the gun stores clashed with them to protect the guns, Kuol said. So in the crossfire five civilians and two chiefs were killed. South Sudans semi-autonomous government has launched programmes to collect hundreds of thousands of weapons left over from Sudans two-decade north-south civil war, but has often met resistance from local populations caught up in the escalating violence. The Gok then attacked a separate southern Sudan Peoples Liberation Army (SPLA) base in Cueibert on Saturday afternoon and again on Sunday morning, leaving an unknown number of additional casualties, said Kuol. They were repulsed, but there were casualties on both sides ... Cueibert town was evacuated, he added. The deputy governor of Lakes State David Noc confirmed the seven deaths and said he was waiting for updates from the remote area. Southern leaders have accused their former civil war foes in north Sudan of arming tribal militias to destabilise the region, a charge dismissed by Khartoum. Analysts have suggested leading figures in the south may also be arming fellow tribe members to build up their constituencies. The 2005 peace deal that ended Sudans civil war promised southerners a referendum, due in January 2011, on whether to stay united with the north or split off as a separate country.