Iligan City, Philippines  - A second unexploded bomb was recovered in a southern Philippine city on Sunday, three days after twin explosions killed three people, police said.

The explosive, made from an 81-millimetre mortar shell, was found in a garbage dump in Iligan City, 810 kilometres south of Manila, police said.

It was the second unexploded bomb found in the city since two shopping centres were bombed on Thursday, killing three people and injured scores.

On Friday, a bomb was found inside a bakery just hours after President Gloria Macapagal Arroyo left the city.

Arroyo visited the victims of Thursday's explosion.

Police investigators said the same group was believed to be responsible for all incidents.

Authorities said no group claimed responsibility for the attacks, but they noted that the separatist Moro Islamic Liberation Front (MILF) operates in the area.

The MILF denied involvement in the bombings.

The MILF has been fighting for an independent Islamic state in the southern Philippines since 1978.

Fighting between the rebel group and the military have been on and off since August when the guerrillas launched a series of deadly attacks to protest a setback in peace talks. (dpa)