Cotabato City (Philippines), Oct 21 (DPA) Seven people were killed Thursday in a bombing inside a passenger bus in the southern Philippines, the military and police said.

The bus was travelling along a national highway in Matalam town in North Cotabato province, 930 km south of Manila, when the blast occurred.

Lieutenant Colonel Randolph Cabangbang, a regional military spokesman, said six passengers were wounded in the attack, believed to have been perpetrated by extortionists.

‘The bus company has long been receiving extortion letters from armed groups operating in the region,’ he said.

Chief Superintendent Gil Meneses, a regional police commander, said at least 50 people were aboard the Rural Transit bus when the explosion occurred.

He said the bus was travelling to nearby Tacurong City from Cagayan de Oro when it made a stopover in Matalam town.

‘The bomb must have been planted in the bus during the stopover,’ Meneses said.