Refugees say Sudan's armed forces are attacking villages in the Blue Nile border state with warplanes, helicopters and troops, killing civilians and torching settlements, in a counter-insurgency campaign that rights activists say could include war crimes. (..) The fighting between government forces and rebels, whom Khartoum accuses the South of backing, has complicated already-fraught talks between the two countries to resolve a raft of issues related to partition. It has also alarmed aid agencies who fear a humanitarian disaster in Blue Nile and in South Kordofan, another border state, as food stocks dwindle.