Cotabato City, Philippines - Seven people were wounded when an improvised bomb exploded in a southern Philippine city, a local official said Monday.

The bomb exploded Sunday evening on a pedestrian overpass bridge in Kidapawan City in North Cotabato province, 960 kilometres south of Manila, according to Vice Governor Emmanuel Pinol.

All victims who suffered wounds from the explosion are in stable condition.

Pinol said the explosion was powerful and created a hole on the concrete overpass bridge.

Some glass windows of nearby buildings were partly damaged by the explosion.

Pinol said police were still determining the motive behind the attack, including the possibility that the attack was perpetrated by secessionist Moro Islamic Liberation Front (MILF) rebels.

The 12,000-strong MILF has been fighting for an independent Islamic state in Mindanao since the 1978. It entered into peace negotiations with the government in 1997. (dpa)