Fifteen thousand people have been displaced by Wednesday's eruption of Mt Ulawun, the governor of Papua New Guinea's West New Britain province says.
Villages and plantations that surround the mountain have been coated in ash, killing crops and contaminating water supplies, as well as forcing local villagers to flee.
The governor, Francis Maneke, said ash had spread as far as the provincial capital Kimbe, some 200km away.
The displaced people desperately need supplies, but with the airport closed and the only access a dirt road, relief could be slow to arrive, Mr Maneke said.
"The most urgent ones will be food, water and also medical support. And also maybe logistics, transport, in order to get the supplies to the area," he said.
"That's the problem now, we don't have access to the provincial airport. It will not be cleared for some time."
The governor said he was appealing to the national government to declare a State of Emergency.