Cotabato City, Philippines  - A homemade bomb ripped through a passenger bus terminal in a southern Philippine city Sunday, but no one was hurt, police said.

The explosion occurred before dawn at the Husky Bus Terminal in Cotabato City, 960 kilometres south of Manila, according to Senior Superintendent Willie Dangane, city police chief.

Dangane said two buses and a concrete wall were partially damaged by the blast.

"Police investigators are looking into extortion and transport business rivalry as possible motives," he said.

Extortion groups have in the past bombed passenger buses and terminals in the southern Philippines when owners refuse to pay up, killing dozens of people.

Islamic militants have also been blamed for previous attacks on transportation systems in the southern Philippines, home to a decades-old Muslim insurgency. (dpa)