A magnitude 6.9 earthquake struck off the coast of the southern Philippines early Monday, the United States Geological Survey said, the latest in a slew of strong quakes all concentrated in the same area.

Monday's quake hit just before 4:00 am local time, (2000 GMT Sunday), at a depth of 30 kilometres (18 miles), about 72 kilometres northeast of Hinatuan municipality on Mindanao island.

That followed a magnitude 6.6 earthquake on Sunday and a deadly magnitude 7.6 quake Saturday in the same region, which had briefly triggered a tsunami alert.

At least two people were killed and several were injured after Saturday's quake, authorities said. It was followed by a series of aftershocks of magnitudes exceeding 6.0 through Sunday, according to the USGS.

"The quake was brief, it lasted around six seconds, but the shaking was quite strong," said Allan Luna, a disaster officer in Cagwait municipality, about 35 kilometres from the epicentre of Monday's tremor.

"The other night people panicked. But this morning, since they've experienced a similar quake already, they calmly went out of their houses and stayed outdoors for around an hour."

Hinatuan police Staff Sergeant Joseph Lambo said Sunday evening's quake sent people rushing out of their homes again.

"They were panicking due to the memory of the previous night's quake," Lambo told AFP.

Saturday's quake triggered tsunami warnings across the Pacific region and sent residents along the east coast of Mindanao fleeing buildings, evacuating a hospital and seeking higher ground.

- Collapsed wall kills man -

Some walls and roads cracked while a number of flimsy homes crumpled and the roof of an outdoor court collapsed, but there have been no reports of major damage so far, disaster officials in the quake-affected region have told AFP.

A 30-year-old man died in Bislig City, in Surigao del Sur province, when a wall inside his house fell on top of him, said local disaster official Pacifica Pedraverde.

A pregnant woman was killed in Tagum city in Davao del Norte province, the national disaster agency said, without providing details.

Two people suffered minor injuries from falling debris in Tandag City, about 100 kilometres north of Bislig, an official said.

The Philippine seismology institute initially warned of a "destructive tsunami" after the first quake Saturday, expecting "life threatening" waves, though none occurred and the warning later ended.

Small swells were reported as far away as Japan's eastern Pacific coast, where a tsunami warning was also briefly in effect. Palau, a western Pacific archipelago located about 900 kilometres off Mindanao, reported no impact.

Over 100 aftershocks above magnitude 3 have been recorded since the M7.6 mainshock in the Philippines. This animation shows the seismicity sequence thus far. The Philippines are an earthquake-prone region, located where the Philippine Sea Plate subducts beneath the Sunda Plate. pic.twitter.com/CEIKomOGJP
— EarthScope Consortium (@EarthScope_sci) December 3, 2023

The recent earthquakes came about two weeks after a 6.7 magnitude tremor hit Mindanao, killing at least nine people, shaking buildings and causing part of a shopping mall ceiling to collapse.

Earthquakes are a daily occurrence in the Philippines, which sits along the Pacific "Ring of Fire", an arc of intense seismic and volcanic activity that stretches from Japan through Southeast Asia and across the Pacific basin.