BEIRUT (Reuters) -At least six people were killed in two days of clashes in a Palestinian refugee camp in Lebanon, where the mainstream faction Fatah fought against rival groups that support Islamists, security sources said. A Fatah commander was killed on Sunday in an ambush that also injured several of his aides in the crowded, impoverished Ain el-Hilweh camp near the southern Lebanese coastal city of Sidon. Four of the aides later died of their injuries, a security source said, adding sporadic clashes in the camp intensified later on Sunday.