A strong offshore earthquake has rattled the southern Philippines but no damage or injuries have been reported.

Renato Solidum, director of the Philippine Institute of Volcanology and Seismology, says the magnitude 6.1 tremor struck at 11:20 a.m. (0320 GMT) Thursday.

Solidum says it was centered at sea about 53 miles (85 kilometers) southeast of General Santos at a depth of 115 miles (184 kilometers), too deep to generate a tsunami or cause damage.

It was felt strongest in General Santos city, about 640 miles southeast of Manila.

The Philippine archipelago lies in the so-called Pacific Ring of Fire where quakes are common.