Police swarmed the bloodied, upturned baggage check-in counters of the Unity store and the neighbouring Gerry's Shoppers' Plaza in downtown Iligan to collect evidence shortly after the early afternoon blasts, an AFP photographer on the scene said.

Local police investigators and witnesses said the bombs went off within 15 minutes of each other.

Two people, including a baggage counter clerk at one of the stores, were killed, Master Sergeant Armando Amoroso, a military investigator on the scene, told AFP.

Thirty people were being treated at the Doctor Uy hospital for blast injuries, hospital staff said, while six other injured people were awaiting transport from the scene of the blast, an AFP reporter on the scene said.

Investigators had no immediate motive or suspects.

The southern Philippines region of Mindanao is the hotbed of a decades-old Muslim separatist insurgency that has, in recent years, been suspected of harbouring Islamic militants with ties to the Al-Qaeda network of Osama bin Laden.

Iligan is Muslim-Christian entrepot of about 300,000 people on Mindanao island's north coast. -- AFP