The governor of Oro in Papua New Guinea says about half of the population in the flood-struck province haven't received relief supplies yet.
164 people have been confirmed dead and thousands have been left homeless after floods submerged the province two weeks ago.
A major airlift of relief supplies, using Australian Army helicopters, got underway last Monday.
Governor Suckling Tamanabae says although aid agencies have distributed tonnes of food and medicine, there are still areas they couldn't reach.
"[The] areas that were devastated, there are a whole lot of challenges to be faced. What they are doing now is delivering food and water as fast as they can but that's half of the population and there is still [another] half that we have to work on."
Suckling Tamanabae says he is also worried about water-borne diseases as he says there are many people with diarrhoea.