Jakarta  - The powerful undersea earthquake that struck Indonesia's North Sulawesi province and nearby regions early Monday killed at least one person, injured three others and collapsed hundreds of buildings, officials said.

The quake at 01:02 am (1702 GMT Sunday) measured 7.7 on the Richter scale. Its epicentre was located about 138 kilometres north- west of Gorontalo on North Sulwesi, about 1,950 kilometers east- northeast of Jakarta. It occurred about 10 kilometres beneath the seabed.

The US Geological Survey recorded the quake at 7.5 on the Richter scale.

Indonesia's National Meteorology and Geophysics Agency (BMG) briefly issued a tsunami warning, but the alert was canceled about an hour later, after no tidal waves materialized, an official said.

A series of aftershocks followed the powerful quake, with the highest measuring 6.0 on the Richter scale, sparking a further panic among residents and preventing them from returning to their homes.

Thousands of residents in Gorontalo, Palu and other regions remained outdoors six hours after the quake. They were staying in the hills for fear of tidal waves despite the lifting of the official tsunami warning.

"The residents had fled to available hills around their houses since the first earthquake happened," the state-run Antara news agency quoted Risan Dewanto, the coordinator of disaster management in northern Gorontalo district, as saying. He added three people were injured after being hit by falling house debris.

In Buol regency in central Sulwesi province more than 300 homes collapsed. More than 20,000 residents fled their homes, the state-run Antara news agency and Elshinta private radio reported.

At least one person was killed in the quake and a number of school buildings collapsed in northern Gorontalo, Rustam Pakaya of the crisis centre at the Health Ministry said.

Pakaya said the team of health officials were still collecting more data from the affected areas.

Hotel guests and residents in Gorontalo city also abandoned buildings and fled to higher ground to escape possible tidal waves.

Indonesia, the world's largest archipelago, sits on the Pacific "Ring of Fire," the edge of a tectonic plate prone to seismic upheaval.

The country launched a new high-tech system early last week aimed at detecting potential tsunamis and providing faster alerts in a region battered by frequent earthquakes.

A major earthquake and subsequent tsunami struck in December 2004, leaving more than 170,000 people dead or missing in Indonesia's Aceh province and around 500,000 homeless. (dpa)