MANILA: A magnitude 6.7 earthquake rattled the southern Philippine region of Mindanao on Friday, the German Research Center for Geosciences (GFZ) said, and while there were no immediate reports of casualties, authorities warned of damage.

The quake struck off the shore of Mindanao, near General Santos City at a depth of 60 km (37.3 miles), GFZ said. The German agency earlier reported the magnitude at 6.9.

The Philippine seismology agency PHIVOLCS and the Pacific Tsunamic Warning Center said a tsunami was not expected.

Amor Mio, police chief of Koronadal city, near the quake’s epicentre, said there were no reports of casualties but officials were checking a shopping mall reported to have been damaged.

“The employees were ordered evacuated for their safety. According to police in the area, there was extensive damage but we could not ascertain definitely yet the extent,” Mio said by telephone.

PHIVOLCS director Teresito Bacolcol told DZRH radio the earthquake’s intensity was “destructive, so we would expect damage”.

The earthquake lasted several seconds, he said, advising residents to be on alert for aftershocks as strong as magnitude 6.2.

Radio announcer Leny Aranego in General Santos city said the quake damaged walls and toppled computers from desks.

“We saw how the walls cracked and computers fell,” Aranego told DZRH radio station.

Michael Ricafort, an economist at the lender RCBC, said in a Facebook post passengers at the airport in General Santos City were evacuated to the tarmac.

Earthquakes are common in the Philippines, which lies on the “Ring of Fire”, a belt of volcanoes circling the Pacific Ocean that is prone to seismic activity.