Mass burials have begun for the hundreds of victims of the earthquake and tsunami that hit the Indonesian city of Palu, as relatives of the missing comb thorough body bags for their loved ones.

Key points: Mass burials are beginning for "health and religious" reasons

Mass burials are beginning for "health and religious" reasons The grave being dug in Palu is 10 by 100 metres and can be enlarged to accommodate more bodies

The grave being dug in Palu is 10 by 100 metres and can be enlarged to accommodate more bodies The death toll is expected to rise as authorities gain access to isolated areas

The current death toll of 844 is largely from the city of Palu and is expected to rise into the thousands as areas cut off by the damage are reached.

In a desperate attempt to stave off the spread of disease in the devastated region, Indonesia's national disaster mitigation agency authorised the burials to proceed as soon as possible.

All of the victims, coming from local hospitals, have been photographed to help families locate where their relatives are buried.

Local Army Commander Tiopan Aritonang said 545 bodies would be brought from one hospital alone, but that only some would be buried on Monday.

The grave being dug in Palu will be 10 by 100 meters and can be enlarged if needed, said Willem Rampangilei, chief of Indonesia's National Disaster Mitigation Agency.

"This must be done as soon as possible for health and religious reasons," he said.

The Palu mass grave can accommodate up to 1,000 bodies and can be enlarged if required. ( Reuters: Antara Foto )

Local military spokesman Mohammad Thorir said the area adjacent to a public cemetery on a hill can hold as many as 1,000 bodies.

Indonesia is a majority Muslim country, and religious custom calls for burials soon after death, typically within one day.

Meanwhile, nearly 50,000 people remain displaced and various parts of the nation "paralysed" amid the recovery efforts.

Disaster agency BNBP said it had "limited data, information and access" to the affected areas.

"The electricity and communication conditions for Palu, Donggala, Sigi and Parigi Moutong are also paralysed," spokesman Sutopo Purwo Nugroho said.

He added 144 foreign nationals were in Palu and Donggala during the earthquake and tsunami.

Palu airport will soon be re-opened for limited flights to aid the recovery efforts.

Sorry, this video has expired Buildings left flattened in Palu

Girl trapped in rubble beside her dead mother

There is also a desperate need for heavy equipment to reach possible survivors buried in collapsed buildings, including an eight-storey hotel in Palu where voices were heard in the rubble.

A 25-year-old woman was found alive on Sunday evening in the ruins of the Roa-Roa Hotel, according to the National Search and Rescue Agency, which released photos of the her lying on a stretcher covered in a blanket.

Many buildings, including this mosque in Palu, were destroyed by the tsunami. ( AP/Antara Foto Agency )

But the cries from beneath the Roa-Roa Hotel, which appeared to have toppled over with its walls splintered like pickup sticks, went silent by Sunday afternoon. Officials had estimated about 50 people could be inside.

"We are trying our best. Time is so important here to save people," said Muhammad Syaugi, head of the national search and rescue team.

"Heavy equipment is on the way."

Sorry, this video has expired Man pulled alive from rubble three days after quake and tsunami

A number of other survivors were still being found and a few were being pulled from buildings in different locations.

Metro TV showed about a dozen rescuers in orange jumpsuits climbing over debris with a stretcher carrying the body of a victim from the modest business hotel.

Rescuers have been working to save people trapped in flood waters and rubble. ( AP: Arimacs Wilander )

Other rescuers worked to try to free a 15-year-old girl trapped under concrete in her house in Palu after it collapsed on her family during the earthquake.

Unable to move her legs under the rubble, Nurul Istikharah was trapped beside her dead mother and niece.

Rescuers also tried to control water from a leaking pipe, fearing she would drown.

Ms Istikharah was unconscious during part of the effort to free her, but rescuers kept talking to her to try to keep her awake. Others offered her food and water.

Meanwhile in Donggala, about 70 kilometres north of Palu, Andi and Flarahaine Rainaldi were able to locate the body of their only son Rafi.

Map Waves between three and six metres high were recorded at Palu and Donggala.

He had been playing with the couple's two nieces at their house near the epicentre of the earthquake when it began to shake.

"I'm so devastated. He was my only son, my only child. And he's just a little boy. I miss him so much. It's very hard to lose him," Mr Rainaldi said.

"We'll bury them all as soon as possible."

People survey the damage outside a Palu shopping mall. ( AP: Tatan Syuflana )

Widodo accepts international aid

Indonesian President Joko Widodo authorised for the country to accept international help for the disaster, Thomas Lembong, chair of Indonesia's Investment Coordinating Board, tweeted on Monday morning.

It was not immediately clear what type of help was being authorised, but the stricken areas needed medical supplies, fuel, fresh water and experts.

It was the latest natural disaster to hit Indonesia, which is frequently struck by earthquakes, volcanic eruptions and tsunamis because of its location on the "Ring of Fire," an arc of volcanoes and fault lines in the Pacific Basin.

In December 2004, a massive magnitude-9.1 earthquake off Sumatra in western Indonesia triggered a tsunami that killed 230,000 people in a dozen countries.

More recently, a powerful quake on the island of Lombok killed 505 people in August.

Sorry, this video has expired Fishermen flee inland as tsunami hits Indonesian coastline

ABC/AP