South Sudan's defense minister said on Friday the leader of rebels battling government forces did not have enough control over his fighters to make any ceasefire hold, as peace talks dragged on with no sign of a deal. Defense Minister Kuol Manyang Juuk also told Reuters the two sides were still fighting over two strategic towns and said his government could ask Sudan for military help if the conflict in the world's newest nation threatened South Sudan's oilfields. Sudan, from which the south split in 2011, relies on revenues from fees charged for use of its pipeline that carries South Sudan's oil exports to international markets.