A powerful earthquake has killed at least four people in the southern Philippines and injured more than 120 others.

The earthquake has damaged buildings, including an airport, and knocked out power.

The quake struck today with a magnitude of 6.5 roused residents from sleep in Surigao del Norte province on the island of Mindanao, sending hundreds to flee their homes.

The quake was centred about 14 kilometres northwest of the provincial capital of Surigao at a relatively shallow depth of 11 kilometres, said Renato Solidum of the Philippine Institute of Seismology and Volcanology.

Nearly 100 aftershocks have been felt, officials said, adding schools were being reopened as evacuation centres for residents wary of returning to their damaged homes.

Solidum said the quake was set off by movement in the Philippine fault, which sits in the Pacific "Ring of Fire", where quakes and volcanoes are common.

At least four people were killed, some after being hit by falling debris and blunt objects, provincial disaster-response official Gilbert Gonzales said, correcting an earlier report by a regional hospital that listed 15 residents who were rushed in with injuries as dead.

At least 126 others were injured in Surigao city, about 700 kilometres southeast of Manila.

"We're still doing a rapid needs and damage assessment," Office of Civil Defence director Antonio Gonzales said.

Several mostly low-slung buildings and schools sustained cracks in the coastal city and a bridge collapsed in an outlying town.

Rescue teams were checking for possible casualties in a village called Poknoy in the city of 140,500 people, he said.

The city's airport was temporarily closed due to cracks in the runway, aviation officials said.