JAKARTA: A strong 6.1-magnitude earthquake rattled Sulawesi in Indonesia on Tuesday, seismologists said, but there was no tsunami alert and no immediate reports of damage.

The quake hit at 9:33 pm (1333 GMT) at a depth of 20 kilometres (12 miles), the US Geological Survey said, 255 kilometres southeast of Palu, on Sulawesi.

There were no tsunami advisories in place, according to the Hawaii-based Pacific Tsunami Warning Center.

Indonesia sits on the Pacific "Ring of Fire", where the meeting of continental plates causes high seismic activity.