It was not immediately clear if the guerrillas had shot it down or if the aircraft went down due to any other reason, the sources said.
"The UAV crashed somewhere near Mankulam, a short distance away from where the Tigers have a clandestine airstrip," a military source said.
Operating spy missions over rebel territory is a violation of a ceasefire agreement that went into effect in February 2002.
Despite the truce, hundreds of people have been killed in violent clashes blamed on both sides as well as a breakaway faction of the guerrillas.
-Amal Jayasinghe: win98win@gmail.com