Iligan City, Philippines - A power outage hit a large portion of the strife-torn southern Philippines on Saturday after armed men bombed a pylon in the area, a power official said.

Engineer Avelino Dawis, a local manager of the National Transmission Corp, said a steel pylon in Kauswagan town in Lanao del Norte province, 810 kilometres south of Manila, was toppled by three homemade bombs strapped on its base exploded early Saturday.

He said a fourth bomb, made from an 81-millimetre mortar shell, did not explode and was successfully detonated by military bomb experts.

The areas without electricity included the Zamboanga peninsula, Misamis Oriental province and some portions of Lanao del Norte, according to Dawis.

Dawis said repair on the damaged structure had not yet started since power officials need to get clearance from Muslim secessionist rebels who control the area.

Investigators were eyeing extortion as the motive behind the attack.

Dawis said the bombing of the tower in Kauswagan was the first this year. In 2008, gunmen bombed 38 steel pylons in Mindanao. (dpa)