Eighty-five others were injured and dozens of homes and commercial buildings were reportedly damaged by the quake, but officials said there was no tsunami threat.

Helicopters are dropping disinfectant on neighbourhoods in the earthquake- and tsunami-stricken city of Palu to reduce disease risks from the thousands of victims believed buried in obliterated communities, Indonesia's disaster agency said Thursday.

The official death toll had risen to 2,073 as of Thursday, with most of the fatalities in Palu.