SYDNEY, May 27 (Reuters) - More than 2,000 people were

buried alive by a massive landslide in Papua New Guinea last

week, the national disaster centre said on Monday, as

treacherous terrain and the difficulty of getting aid to the

site raises the risk few survivors will be found.

The numbers of those buried around Yambali village in Enga

province in the country's north are based on estimates from

local authorities which have been rising steadily since Friday's

landslide.

A U.N. agency put the estimated death toll at more than 670

people on Sunday.

The National Disaster Centre raised the toll again to 2,000

in a letter to the U.N. on Sunday that was released publicly on

Monday. The landslide also caused major destruction to buildings

and food gardens, it said.

"The situation remains unstable as the landslip continues to

shift slowly, posing ongoing danger to both the rescue teams and

survivors alike," according to the letter.

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.

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 U.N. 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.

"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.

DANGEROUS CONDITIONS

Water continued to flow under the debris, the U.N. migration

agency said, making it extremely dangerous for residents and the

rescue team to clear debris.

Serhan Aktoprak, the chief of the U.N. migration agency's

mission in PNG, told ABC television that emergency crews would

continue to look for survivors until the residents asked them to

stop.

Aktoprak said that the rescue team had eight vehicles but

that he hoped to receive additional resources soon.

Tribal violence in the region has raised security concerns

for road travel, with the military escorting convoys of rescue

teams. Eight people were killed, and five shops and 30 houses

burnt down on Saturday, the U.N. agency said.

PNG gave arrest powers to its military in February amid an

eruption of tribal violence that saw at least 26 men killed in

an ambush.

The landslide hit a section of highway near the Porgera gold

mine, operated by Barrick Gold ( GOLD ) through Barrick Niugini

Ltd, its joint venture with China's Zijin Mining.

Barrick has said the mine has enough fuel on site to operate for

40 days and other critical supplies for longer.