There were no immediate reports of damage and officials said no tsunami warning had been issued.

Indonesian officials said the quake struck at 4.08pm Singapore time, 91 kilometres (56 miles) southwest of Gorontalo in North Sulawesi, at a depth of 32 kilometres.

The US Geological Survey measured the quake at a magnitude of 5.5.

The quake was felt in the towns of Luwuk and Gorontalo on Sulawesi, meteorologist Nurhayati told AFP, but there were no reports of damage.

Indonesia sits on the Pacific 'Ring of Fire' where continental plates meet, causing frequent seismic and volcanic activity.

The archipelagic nation was hardest hit by the earthquake-triggered Asian tsunami in December 2004 which killed an estimated 168,000 people in Aceh province. -- AFP