COLOMBO (AFP) - At least 12 Tamil Tiger rebels were killed by government forces about to capture a key rebel-held town in northern Sri Lanka, the Defence Ministry said Wednesday. Government troops recovered the bodies of six rebels while snipers killed another six as the military moved to the outskirts of the strategically vital town of Paranthan on Tuesday evening, the Ministry said. Troops had already taken control of two villages adjacent to the town, it added. Official sources said government troops were on the verge of entering the town in a move that could cut off supply routes to Tiger positions further north in the Jaffna peninsula. Paranthan is about six kilometres from the military's main objective - the town of Kilinochchi, which is the political capital of the Liberation Tigers of Tamil Eelam (LTTE). The Ministry did not say if security forces suffered casualties in the heavy confrontations on Tuesday. For their part, the Tigers made no comment on the military's claims, but said four civilians were killed and 18 more wounded in two air raids inside areas held by them on Wednesday. The latest fighting came as a government ultimatum to the Tigers - designed to allow some 300,000 civilians in areas under their control to leave and seek shelter in government-held areas - drew to a close on Wednesday President Mahinda Rajapakse announced last week that he would reimpose a formal ban on the Tamil Tigers if civilians were not allowed the freedom to leave by Wednesday. Officials said the government was mulling the ban, which would essentially be symbolic given the scale of the current military offensive against the LTTE and its political capital, Kilinochchi. An original ban on the LTTE was lifted in September 2002 ahead of an Oslo-backed peace process, which collapsed when President Rajapakse pulled out of the truce in January. The Tigers have not formally responded to the government's ultimatum. The group, which is already outlawed by the United States and the European Union, have been waging a drawn-out campaign for independence for Sri Lanka's minority Tamil community.