The quake struck 56 kilometres (35 miles) southeast of the city of Palu at around 5:40 pm (0940 GMT) at a depth of 20 kilometres.

There were no immediate reports of damage or casualties but panicked residents in Palu ran from their homes as the ground shook violently for a few seconds, an AFP reporter said.

Indonesia's Meteorology, Climatology and Geophysics Agency earlier reported the quake's magnitude at 6.2 at a depth of 10 kilometres, with its epicentre in the populated mountainous district of Parigi Moutong.