Forces loyal to a renegade south Sudanese general clashed with government troops, killing at least 14 people, the southern army said on Tuesday. General George Athor rebelled after losing elections in April for the governorship of the oil-producing south's Jonglei state, raising tensions ahead of a referendum on southern independence which is due to take place next month. South Sudan's leader Salva Kiir offered a pardon to Athor in October and both sides had agreed to keep out of each other's way until negotiations were concluded. "George Athor's forces laid an ambush for an SPLA (southern army) company in Pigi county in Jonglei state," said southern army spokesman Philip Aguer, adding that the attack took place early on Saturday. "This happened in the middle of talks with George Athor. But this incident will be treated separately and amnesty negotiations will continue." Aguer did not have information on what caused the attack and Athor did not answer calls to his satellite phone. Aguer said some southern solders were among the dead and injured but did not have figures and details of the clash were still emerging from the remote area. "We are still investigating ... At least 14 people were killed, maybe more," he said. French oil group Total holds a largely unexplored concession in Jonglei. Kiir said he was offering the pardon to Athor and other rebellious militia leaders to give the region a fresh start ahead of the referendum, promised under a 2005 peace deal that ended decades of civil war with the north. Most southerners are expected to choose to separate from the north. The north-south civil war also saw fighting between rival southern clans and militias and there have been fears these could re-emerge in the uncertainty surrounding the plebiscite. Sudan's north-south war -- Africa's longest civil conflict -- was fuelled by differences over religion, ethnicity, oil and ideology. It killed an estimated 2 million people, forced 4 million to flee and destabilised much of east Africa (Reporting by Jeremy Clarke; writing by Andrew Heavens; editing by Giles Elgood) Source: Reuters