A tsunami warning has been issued in the wake of an undersea earthquake off the Philippines.

The 7.2-magnitude quake struck off the coast of the southern island of Mindanao at 8.23pm (GMT) on Friday (28 April). There have been no reports of casualties.

The Pacific Tsunami Centre has warned that the epicentre of the quake, which was measured at a depth of 10km, was 68km south of the city of General Santos.

It would produce "hazardous waves" that could spread 300km (190m) away from the epicentre, threatening coastal towns and villages in the Philippines and Indonesia.

The US Geological Survey (USGS) later revised the magnitude down to 6.8.

Residents of threatened coastal areas have been urged to stay alert for information and follow instructions from authorities, Sky News reports.

The quake struck in the so-called Ring of Fire, a vast area in Southeast Asia which is prone to regular, and deadly, seismic distrubances.

On Boxing Day 2004, at least 230,000 people in 13 Indian Ocean countries were killed by a tsunami that followed a huge earthquake in the waters off Aceh province, Indonesia.