Image copyright Reuters Image caption Manaro Voui has been in an "moderate eruption state" since Saturday

An erupting volcano in Vanuatu has sparked an unprecedented evacuation of an entire island.

All 11,000 residents of Ambae have been told to leave and will be moved to other islands in the Pacific state.

The Manaro Voui volcano, which has been rumbling for days, began spewing ash in a "moderate eruption" over the weekend.

Officials had moved 6,000 residents to shelters elsewhere on Ambae earlier this week, but have now ordered a full-scale evacuation.

All islanders are expected to have been moved off Ambae by next Friday, in what emergency officials said would be a first for the country.

Image copyright Reuters Image caption Aid workers have been assisting residents in Ambae as they prepare to leave

Authorities had raised their alert to the second highest level on Saturday, meaning Manaro Voui was in a "moderate eruption state". They warned of "flying rocks and volcanic gas", acid rain, and ash falls.

The volcano has been seen emitting clouds of smoke with signs of hot lava emerging to the surface in its crater in recent days.

Image copyright Reuters Image caption This aerial photo captured on Monday shows what appears to be lava in the volcano's crater

Shadrack Welegtabit, director of the national disaster management agency, told AFP news agency: "We have already moved people out of the high ground to safe areas in the west and the east [of the island]."

He said the likelihood was that the volcano would trigger the highest level warning with a full eruption, "[so] we have to get people off the island".

Most people will likely be relocated to the neighbouring island of Pentecost, reported Radio New Zealand.

Manaro Voui last erupted in 2005, prompting 5,000 people to flee their homes.

The volcano - like Bali's Agung, which is showing signs of imminent eruption - sits on the Pacific Ring of Fire.

The geologically active area experiences earthquakes regularly, and has hundreds of active volcanoes.