The death toll from a strong earthquake in the southern Philippines has risen to seven, disaster and police officials said today, as aftershocks continued to jolt many parts of Mindanao.

The 6.6 magnitude quake hit early today, damaging buildings, toppling power lines and triggering landslides in the central area of the Philippines' southern island.

A seven-year-old child and his 44-year-old father were among those who were killed in the North Cotabato province after they were struck by a boulder, disaster officials said.

Authorities said the death toll could rise further because many injured were not immediately brought to hospitals.

"It was depressing to see the damage left by the earthquake," Abril Espadera, a disaster official in North Cotabato, said as he recalled seeing collapsed homes and demolished buildings in the province.

Smaller tremors rattled nervous residents throughout the day and those who were afraid to return to their homes set up tents to shelter near school yards, Mr Espadera said.

In Magsaysay town, in Davao del Sur province, rescuers were trying to recover three bodies after landslides in two separate towns swallowed parts of agricultural areas, police said.

The quake, whose magnitude was initially put at 6.7 by the European-Mediterranean Seismological Centre, was the second powerful quake to strike Mindanao in two weeks.

Authorities had flagged the risk of landslides after the 6.3 quake on 16 October in central Mindanao that killed seven and injured more than 200.

Earthquakes are common in the Philippines, which is on the geologically active Pacific Ring of Fire.

President Rodrigo Duterte's office called for calm as it mobilised all government agencies to undertake damage assessment and to coordinate rescue and relief operations.