Authorities are trying to establish evacuation centres on safer ground on either side of the massive swath of debris.

Serhan Aktoprak, the chief of the United Nations agency’s mission in the South Pacific island nation, said on Sunday the revised death toll was based on calculations by Yambali village and Enga provincial officials that more than 150 homes had been buried by Friday’s landslide.

The previous estimate had been 60 homes.

“They are estimating that more than 670 people [are] under the soil at the moment,” Aktoprak said.

“The situation is terrible with the land still sliding. The water is running and this is creating a massive risk for eveyrone involved,” added Aktoprak, who is based in capital, Port Moresby.

Local officials had initially put the death toll on Friday at 100 or more. Only five bodies and a leg of a sixth victim had been recovered by Sunday, while seven people, including a child, had received medical treatment.

Meanwhile, emergency responders were moving survivors of the massive landslide to safer ground as tonnes of unstable earth and tribal warfare, which is rife in the country’s highlands, threatened the rescue effort.

Damage to infrastructure also made it more difficult for rescue and relief efforts to reach the area, according to Justine McMahon, a CARE Australia humanitarian group representative in PNG.

“The ground is quite unstable, making it difficult for rescuers to get in. The main road has also been cut off by about 200 metres [656 feet], hampering relief,” she told Al Jazeera.

Car-sized boulders

Heavy earth-moving equipment are yet to arrive at the mountainous location 600km (370 miles) northwest of Port Moresby.

At some points, the landslide – a mix of car-sized boulders, uprooted trees and churned-up earth – was thought to be 8 metres (26 feet) deep.

Aid agencies said the catastrophe had effectively wiped out the village’s livestock, food gardens and sources of clean water.

Government authorities were trying to establish evacuation centres on safer ground on either side of the massive swath of debris that covers an area the size of three to four football fields.

“The land hasn’t settled yet,” McMahon told Al Jazeera.

Besides the blocked highway, convoys that have transported relief have faced risks related to tribal fighting in one village about halfway along the route. PNG soldiers were providing security for the convoys.

The government is expected to decide by Tuesday whether it will officially request more international help.

The United States and Australia, a near neighbour and PNG’s most generous provider of foreign aid, are among governments that have publicly stated their readiness to do more to help the responders.