The Papua New Guinea Red Cross says the death toll from widespread flooding in Oro Province could be as high as 100.
The province has been the worst hit by Cyclone Guba, which is continuing to have an impact on PNG.
The flooding has affected thousands with at least two villages completely submerged, while roads, bridges and food gardens have been washed away.
The acting secretary general of the PNG Red Cross, Gima Kila, says clear details are not yet available but he fears the death toll could reach a hundred with thousands left homeless.
He says they are flying up water containers and tarpaulins and appealing for more help.
"We are already getting assistance from the Australian Red Cross. The Japanese Red Cross - we are getting assistance from them already. And we are going to appeal for more assistance based on what assessments we receive."