Vanuatu's Prime Minister has ordered a compulsory evacuation of the population of Ambae due to the volcanic threat.

Photo: Dan McGarry/ Vanuatu Post

Prime Minister, Charlot Salwai, says he expects the mass evacuation of up to eleven thousand people to begin immediately and be completed by 6 October.

Media director of the Vanuatu Daily Post Dan McGarry said most people will be relocated to two publicly owned stretches of land on the neighbouring island of Pentecost.

"They'll be travelling by ship, that's the only reasonable way to ferry that number of people involved. In conjunction with this exodus they will be issuing travel restrictions in the immediate area so that people won't be able to travel in to the affected area and this should facilitate the flow of people."

Mr McGarry said the Prime Minister had taken the precaution in order to potentially save lives given the volcano's unpredictability.

The alert level for the erupting Monaro volcano was raised to four recent days - level five is the highest - and Vanuatu's Meteorology and Geohazards Department warned of flying rocks, volcanic gas, acid rain and ash falls.

Plumes of smoke, ash and volcanic rocks have been filmed erupting from its crater by New Zealand Defence Force (NZDF) aircraft which flew over the island on Tuesday.

A state of emergency was declared, but authorities have said they were struggling to cope.

Photo: Dan McGarry/ Vanuatu Post

Vanuatu Red Cross coordinator Dickenson Tevi said shipping vessels were on standby awaiting the outcome of the Council of Ministers' meeting.

He said it was likely Ambae's population of 10,000 would be evacuated to neighbouring islands.

"The whole island itself, it is not safe with the way the activity has been ongoing at level four until now.

"So we are just waiting on the Council of Ministers' decision this morning and there might be a major change of plans."

Photo: Facebook / Vanuatu Red Cross

Mr Tevi said people had been displaced before due to eruptions but there had never been a complete evacuation of the population of any island.

Before the evacuations get underway though the Vanuatu government is appealing for food aid for the many thousands of Ambae residents now living in shelters on the island.

Our correspondent says food is desperately needed and the government is seeking non-perishable items that can tide people over until food crops from other Vanuatu islands can be obtained.

The MP for Ambae Jacob Mata said he was really concerned about people's lives.

Mr Mata said many people had already left the island but those who did not want to leave may have no choice.

He said there were about 8000 people still on Ambae and most were in shelters near the sea shore preparing in case of evacuation.

"Since the eruptions in the last three weeks probably I can guess about 15 to 20 per cent of the population has already gone. So probably another eight thousand are still here. But it will probably take them about three to four days maybe, it depends on how the operations will go on."

Mr Mata said the island's volcano had a history of large eruptions with one in the 1860s causing a lot of damage.