An improvised bomb tore through a hotel in the southern Philippine city of Cotabato, injuring two people and causing extensive damage, police said on Wednesday.
The bomb exploded late on Tuesday at the Agong Lodging House and destroyed four rooms, said city police chief Senior Superintendent Willie Dangane.
Injured were hotel manager Dagadas Pantao, 52, and employee Teng Wali. Both are in a hospital with shrapnel wounds but are said to be out of danger.
It was not clear who was behind the attack, but Pantao told police from his hospital bed that the room where the bomb was left was occupied by a guest who did not register his name with hotel staff last on Saturday.
Military and police ordnance experts said the bomb could have been fashioned from a 60-millimetre (2.4 inch) mortar rigged to a timing device, a contraption commonly used by Islamic militants in the south.
Pantao said the explosion was so strong it shook the three-storey building.
"I thought it was going to collapse," he said. "I have no enemy and have not hurt anyone to deserve this kind of treatment."
Muslim separatist rebels from the Moro Islamic Liberation Front (MILF) are known to operate in areas just outside the city, and have been engaged in fierce gunbattles with troops since August.