Iligan City, Philippines  - Three people were killed Thursday and 16 were injured when two homemade bombs exploded in two shopping centres in a southern Philippine city, a local official said.

The bombings occurred 15 minutes apart shortly after lunch in the Jerry Shopping Center and Uni City mall in Iligan City in Lanao del Norte province, 855 kilometres south of Manila, Mayor Lawrence Cruz said.

Cruz said investigators have yet to determine the motive behind the attacks but added that Moro Islamic Liberation Front rebels are active in the province.

Earlier Tuesday, at least two soldiers and three rebels belonging to the Muslim separatist group were killed in a clash in the town of Piagapo in the nearby province of Lanao del Sur. dpa()