Most of the dead have been from Palu, 1500 km northeast of Jakarta but some remote areas have been cut off since Friday's 7.5 magnitude quake triggered tsunami waves, leading to fears the toll could soar.

"There are some main priorities we must tackle and the first is to evacuate, find and save victims who've not yet been found," Widodo told a disaster recovery meeting on the west coast of Sulawesi island on Tuesday.

He said he had ordered the national search and rescue agency to send more police and soldiers into affected districts, some cut off by destroyed roads, landslides and downed bridges.

The official death toll surged to 1234, the national disaster agency said.

The Red Cross said the situation was "nightmarish" and workers venturing into one cut-off area, Donggala, a region of 300,000 people north of Palu and close to the epicentre, indicated it had been hit "extremely hard".

Four badly hit districts have a combined population of about 1.4 million.

In Palu, tsunami waves as high as six metres smashed into the beachfront, while hotels and shopping malls collapsed in ruin and some neighbourhoods were swallowed up by ground liquefaction.

Among those killed were 34 children at a Christian bible study camp.

The government has ordered aid supplies to be airlifted in but there's little sign of help on Palu's shattered streets and survivors appeared increasingly desperate.

According to witnesses, one shop was cleared by about 100 people, shouting, scrambling and fighting each other for items including clothes, toiletries, blankets and water.

At least 20 police at the scene did not intervene. The government has played down fears of looting saying disaster victims could take essential goods and shops would be compensated later.

Rescuers in Palu held out hope they could still save lives.

"We suspect there are still some survivors trapped inside," the head of one rescue team, Agus Haryono, said at the collapsed seven-storey Hotel Roa Roa.

About 50 people were believed caught inside when it was brought down. About nine bodies have been recovered from the ruins and three rescued alive.

A particular horror in several areas in and around Palu was liquefaction, which happens when soil shaken by an earthquake behaves like a liquid.

About 1700 houses in one neighbourhood were swallowed up.

Before-and-after satellite pictures show a largely built-up neighbourhood just south of Palu's airport seemingly wiped clean of all signs of life by liquefaction.

Elsewhere, on the outskirts of Palu, lorries brought 54 bodies to a mass grave dug in sandy soil.

Australian Associated Press