GUWAHATI, India, Jan 8 (Reuters) - An Indian rebel faction attacked a camp housing the head of a powerful rival faction in the northeastern state of Nagaland on Monday and one militant was killed, police and rebels said. They said rebels belonging to the Khaplang faction of the National Socialist Council of Nagaland (NSCN-K) attacked the main camp of the Issac and Muivah faction (NSCN I-M), near Dimapur town in Nagaland state. NSCN I-M Chairman Issac Chishi Swu and his wife, who arrived in India on a rare visit from Bangkok this month, were in "Camp Hebron" and both were safe, a senior intelligence officer said by phone from Kohima, Nagaland's capital. "I have lost one of my boys in the firing which is still going on. Casualties on the other side will be higher," Khughalu Mulatonu, a senior NSCN-K leader, told Reuters by phone from his hideout. The NSCN has been fighting for a separate homeland for Naga tribespeople for nearly six decades. More than 20,000 people have died in the revolt in the Christian-majority state. The Issac-Muivah and Khaplang factions have been maintaining a ceasefire with Indian forces as part of a peace process, but regularly clash in a war of supremacy.