Thirteen suspected Moro Islamic Liberation Front rebels and eight government troopers were killed in fierce fighting in Mamasapano town, Maguindanao yesterday as helicopter gunships pounded rebel positions after a faction of the MILF attacked Army outposts. Army spokesman Maj. Bartolome Bacarro said troops were surrounded in their base, but were "able to hold the line" and that reinforcements were on the way. Fighting broke out late Sunday when about 100 MILF guerrillas under Abdul Rahman Binago simultaneously attacked Army detachments in Linantangan, Mamasapano and Labo-Labo in Sharif Aguak, both in Maguindanao, in violation of a two-year-old ceasefire. Mamasapano is some 60 kilometers south of Cotabato City.Col. Franklin del Prado, Army 6th Infantry Division spokesman, said reports from the field indicated that at least 13 MILF rebels were killed in the counter-offensive. The MILF attack was launched in apparent retaliation for the killing last week of Binago's brother Fides Binago, leader of the Abu Sofia bandit group, in a clash with government troops. MILF spokesman Eid Kabalu said the rebel leadership was trying to contact Binago to get him to pull out. Kabalu said an international team of ceasefire monitors was being rushed to the area to keep the fighting from spreading. "This is an isolated case, and both the MILF and the AFP exerted efforts to stop the incident immediately," Kabalu said.