Last Friday's disaster in the country's remote Enga Province buried about 2000 people, and aid organisation UNICEF says nearly half of them were children.
The organisation's Papua New Guinea representative Angela Kearney told RNZ's Morning Report the operation had moved from rescue into recovery.
With most of the houses in the slip area buried under at least eight metres of dirt and silt there was "really no chance, we don't believe, for any more people to be alive", she said.
"It's a recovery and trying to make the land safe around it."
Kearney expected evacuation zones around the landslide area would need to be extended again today - for the third time - as the land remained unstable.
"There's lots of things happening geologically but at the same time there's absolute human misery."
Enga provincial disaster committee chair and provincial administrator Sandis Tsaka earlier told RNZ Pacific, the landslide was "still very active", which was making recovery efforts difficult.
Thousands of local residents had been told to be ready for evacuation in case of further land movement.
"It's terrible; it's scary," said Tsaka, who has visited the disaster site twice and also flown over it with the national disaster team.
"What used to be a densely populated community area with an abundance of life and schools and kids, is now looking like [the] surface of the moon, a pile of rocks.
"It's sad. It's a level of devastation that we've never seen in this part of the world."
Kearney said UNICEF's focus was on supporting children orphaned by the disaster, many of whom had run away to neighbouring villages in the immediate aftermath of the slip.
"Yesterday ... they began to come back, have a look, and they're just sitting there not talking," she said.
"These kids are so traumatised by the noise, what they've seen, what they've lost, and they're just silent.
She said the organisation's efforts would be focused on ensuring those children were safe and occupied by play during the day.
"It's very cold in the highlands at night."
Fears of further slips
A natural hazard expert warns landslides are common in Papua New Guinea and more could occur in the region where Friday's disaster occurred.
University of Auckland Associate Professor, Martin Brook, told RNZ's Morning Report that rain or another earthquake could trigger more landslides.
"Then a final triggering effect occurs and there's obviously not much warning in this kind of bush-covered, forested terrain."
Friday's landslide, which occurred around 3am, was the largest since a magnitude 7.5 earthquake hit the country's Hela Province in February 2018.
