Locals gather at the site of a landslide at Mulitaka village in the region of Maip Mulitaka, in Papua New Guinea's Enga Province on Sunday. AFP

Papua New Guinea informed the UN on Monday that more than 2,000 people were buried in a massive landslide that swept over a remote village, according to a copy of the letter obtained by the media.

"The landslide buried more than 2,000 people alive and caused major destruction," the country's national disaster centre told the UN office in the capital Port Moresby.

A once-bustling remote hillside village in Enga province was almost wiped out when a chunk of Mount Mungalo collapsed in the early hours of Friday morning, burying scores of homes and the people sleeping inside them.

The landslide caused "major destruction to buildings, food gardens and caused major impact on the economic lifeline of the country", the disaster office said.

The main highway to Porgera Mine was "completely blocked", it said in the letter, which was received by UN officials on Monday morning.

"The situation remains unstable as the landslip continue to shift slowly, posing ongoing danger to both the rescue teams and survivors alike."

An excavator driving towards the site of a landslide at Yambali Village in Papua New Guinea's Enga Province. AFP

The scale of the catastrophe required "immediate and collaborative actions from all players", it said, including the army, and national and regional responders.

It called on UN to inform Papua New Guinea's development partners "and other international friends" of the latest situation.

Assistance should be coordinated through the disaster centre, it said.

About 4,000 people were living near the affected area, CARE International PNG country director Justine McMahon told ABC television on Monday.

But it is difficult to get an accurate estimate of the local population as PNG's last credible census was in 2000 and many people live in remote mountainous villages. The country recently announced a census would be conducted in 2024.

The unstable terrain, remote location and nearby tribal warfare are hampering relief efforts in Papua New Guinea.

This handout photo shows people digging at the site of a landslide at Yambali Village. AFP

Emergency crews, led by Papua New Guinea's (PNG) defence personnel, were on the ground, but the first excavator only reached the site late on Sunday, according to a UN official.

Social media footage posted by villagers and local media teams showed people scaling rocks, digging with shovels, sticks and their bare hands to find survivors. Women could be heard weeping in the background.

Six bodies have been retrieved so far. The U.N. said the number of possible deaths could change as rescue efforts were expected to continue for days.

PNG media on Monday reported that residents had rescued a couple trapped under rubble after hearing their cries for help.

Johnson and Jacklyn Yandam told local NBC News that they were very grateful and described their rescue as a miracle.

Locals are seen near the site of a landslide at Mulitaka village in Papua New Guinea's Enga Province. AFP

"We thank God for saving our lives at that moment. We were certain that we were going to die but the big rocks didn't crush us," Jacklyn said. "It's really hard to explain as we got trapped for nearly eight hours, then got rescued. We believe we were saved for a purpose."

About 1,250 people have been displaced by the landslide, which occurred in PNG's Enga province early Friday. More than 150 houses were buried and about 250 houses abandoned.

"The houses are buried under around eight metres (26.3 ft) of dirt. So there is quite a lot of debris to get through," said CARE's McMahon.