The Philippine armed forces has demanded Muslim rebels in the southern island of Jolo surrender or suffer heavy casualties, as fighting enters its fourth day. More than 100 soldiers and supporters of jailed former Muslim separatist leader, Nur Misuari, have either been killed or wounded in some of the most intense fighting seen in the region for years. Chief of the military's southern command, Lieutenant General Alberto Braganza, says reinforcements dispatched to the area are enough to crush the rebels.Clashes erupted on Jolo island on Monday following attacks by Mr Misuari's men against troops in several towns. They had joined forces with the Abu Sayyaf, who were fighting the troops. The area is a known stronghold of armed Muslim militants and the al Qaeda-linked Abu Sayyaf rebels. The AFP news agency quotes officials as saying that his followers are demanding his detention be transferred to Jolo.