A tsunami up to two metres high hit a small city on the Indonesian island of Sulawesi on September 28 after a major 7.5 quake struck offshore, collapsing buildings and washing a vessel ashore, but officials could provide no information on casualties.

The quake hit as dusk fell and communications were down and the airport closed, making it impossible to assess the damage to life and property, officials said.

National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho said communications had been cut both in the city of Palu, a sleepy but growing tourist resort, and the nearby fishing town of Donggala, closest to the epicentre of the quake 80 km away.

Officials hope to be able to gauge the scale of the damage at daybreak after the strongest of a series of earthquakes that continued late into the evening.

“The 1.5- to two-metre tsunami has receded,” Dwikorita Karnawati, who heads Indonesia's meteorology and geophysics agency, BMKG, told Reuters. “It ended. The situation is chaotic, people are running on the streets and buildings collapsed. There is a ship washed ashore.”

BMKG had earlier issued a tsunami warning, but lifted it within the hour.

Amateur footage shown by local TV stations, which could not immediately be confirmed by Reuters, showed waters crashing into houses along Palu's shoreline.

The national search and rescue agency would deploy a large ship and helicopters to aid with the operation, said agency chief Muhammad Syaugi, adding that he had not been able to contact his team in Palu.