A strong Pacific Ocean earthquake was felt in several southern Philippine cities early today, but officials said they had no reports of damage of casualties.

The Phillippine Atmospheric, Geophysical and Astronomical Services Administration said the six-second quake occured about 750 miles south-south-east of Manila, east of the remote Indonesian island of Palmas.

Seismologist Benito Bunsalan said after shocks were expected, but no tidal wave or other damaging activity had been reported from the original tremor.

The U.S. Geological Survey at Golden, Colo., said the quake registered 6.8 on the Richter scale.

The quake was the strongest to hit the Mindanao area since a 7.1 magnitude earthquake struck the island on Dec. 12, 1978. There were no casualties or significant damage in the 1978 tremor.

On Aug. 16, 1976, between 5,000 and 8,000 persons were killed when a quake registering 7.9 on the Richter Scale struck off the coast of Mindanao.

Meanwhile, in the mid-Atlantic Portuguese Azores, officials said 33 persons were confirmed dead after an earthquake shattered the town on Angra do Herosimo.

U. S. Air Force officers at Lajes, 20 miles away, reported, however, that 52 persons had been killed and more than 400 injured.