The Philippines disaster agency has reported at least 15 fatalities after a magnitude 7.8 earthquake.

Philippine authorities urged people in affected coastal regions to move to higher ground after the offshore quake hit south of General Santos, a city of about 720,000.

A series of powerful aftershocks rocked the area from about two hours after the first quake, according to the United States Geological Survey (USGS), with the largest measuring 6.5 on the Richter scale.

Videos posted to social media and verified by AFP showed a shopping centre with a Jollibee fast food restaurant collapsing into rubble in the province's General Santos City, while a building on a local school campus crumpled in another.

"Lord, it has really collapsed! ... The building has really collapsed!" someone can be heard shouting as the school structure toppled.

The Pacific Tsunami Warning Center said in a notice that tsunami waves were possible "within the next three hours" along the coasts of the Philippines, Indonesia, Palau, Taiwan and Papua New Guinea.

Police Major Roland Catoburan told AFP two people had been crushed to death by a collapsing wall in Alabel, a municipality near General Santos City.

"We have casualties. A wall fell on them," he said, adding officers were not being allowed to re-enter their stations, some of which now had cracked walls.

Master Sergeant Robert Dagon of the General Santos City police separately confirmed another reported death and four injuries.

"Many buildings were affected, but I cannot enumerate them now because we are busy with ongoing rescues," Dagon said.

EVACUATE NOW

Philippine President Ferdinand Marcos suspended school classes in affected areas of Mindanao while calling on residents in coastal areas to evacuate immediately.

"Move to higher ground now. Do not wait," he said. "Your life is more important than anything left behind."

The country's national disaster agency said reports of casualties were "still being verified".

In Kiamba, a coastal town near the epicentre, about 50,000 residents had already done so.

"As of now, 80 per cent of the population has moved to higher ground," Agripino Dacera, the regional disaster chief, said.

"All the villages along the coast were instructed to proceed to evacuation centres."

The airport in General Santos was also closed until further notice, officials said.

Monday's quake triggered evacuation warnings for coastal areas of neighbouring Indonesia and Malaysia, with both nations subsequently lifting their alert.

Japanese authorities issued a tsunami advisory for swathes of its Pacific coast, projecting waves of up to 1m to hit different regions from 11.30am (10.30am, Singapore time).

Earthquakes are a near-daily occurrence in the Philippines, which is situated on the Pacific "Ring of Fire", an arc of intense seismic activity stretching from Japan through Southeast Asia and across the Pacific basin.

Eastern Mindanao was rocked by a pair of earthquakes of 7.4 and 6.7 magnitude in October that killed at least eight people.

These followed a magnitude 6.9 quake days earlier that killed 76 people and destroyed or damaged 72,000 houses in Cebu province in central Philippines, according to government figures.

Source: CNA 

--Agencies