People gather at the site of a massive landslide in Papua New Guinea's Enga province on Friday. [AFP]

Rescue crews arrived at the site of a massive landslide in Papua New Guinea's remote highlands Saturday, helping villagers search for hundreds of people feared dead under towering mounds of rubble and mud.

The disaster struck an isolated part of Enga province around 3:00 am Friday, according to government officials, wiping out swathes of the hillside settlement as villagers slept.

"At this time, we are still searching for bodies who are buried by the massive landslide," local leader Mark Ipuia said Saturday, adding he feared "more than 300" people were buried under the debris.

Both the United Nations and Red Cross have said the death toll could be substantially higher than 100, although they cautioned it could take days until a reliable estimate emerges.

"While verified casualty numbers are still pending, people living in the approximately 60 destroyed homes are unaccounted for," said a UN situation report seen by AFP on Saturday.

So far, at least four bodies have been recovered, a UN official based in the capital Port Moresby told AFP.

"There are a lot of houses under the debris that cannot be reached," said UN official Serhan Aktoprak, who estimated more than 3,800 people lived in the village.

"The land continues to slide and move, and that makes it dangerous for people to operate," he said.

At some points, the landslide - a mix of car-sized boulders, uprooted trees and churned-up earth - was eight metres (26 feet) deep, Aktoprak added.

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

A rapid response team of medics, military and police began pouring into the disaster zone Saturday morning after a journey complicated by the rugged terrain and damage to major roads.

"While the area is not densely populated, our concern is that the death toll could be disproportionately high," humanitarian agency CARE said as the first reinforcements arrived.

'A big problem'

Locals suspected the landslide may have been triggered by heavy rains that have saturated the region in recent weeks.

Papua New Guinea has one of the wettest climates in the world, according to the World Bank, with the heaviest downpours concentrated in the humid highland regions.

Research has found shifting rainfall patterns linked to climate change could exacerbate the risk of landslides in the country.

Images showed a scene of total devastation, with a vast bite of earth cleaved from densely vegetated Mount Mungalo.

Barefoot workers used shovels, axes and improvised tools to loosen and shift the earth, while others picked through mangled piles of corrugated iron that once provided shelter.

Volunteers hauled a covered body away from the scene on top of a makeshift stretcher.

Nickson Pakea, president of the nearby Porgera Chamber of Commerce and Industry, said little progress would be made until the damaged roads were patched up and heavy machinery trucked in.

"The destruction is massive," he told AFP.

"They need machinery and other equipment to uncover these bodies. We are facing a big problem."

'Completely buried'

Pakea said the village was a busy trading post frequented by the alluvial miners who panned for gold in the region.

"It's a centre of the community. People come from near and far to do their alluvial mining, and then they come to this place to trade."

Steven Kandai, a community leader at the scene, told AFP many residents had no time to flee.

"All of a sudden there was a big landslip. The mountain just collapsed all of a sudden while people were still sleeping," he said, adding their homes were "completely buried".

Offers of support have poured in from around the globe.

President Joe Biden said he was "heartbroken by the loss of life and devastation", adding the United States stood "ready to assist" in recovery efforts with partners including Australia and New Zealand.

Prime Minister Anthony Albanese said that "all Australians grieve for our brothers and sisters in Papua New Guinea after the terrible landslide".