Indonesia's Ruang volcano erupts again, shuts down international airport

Indonesia's remote Mount Ruang volcano has erupted several times again, the country's volcanology agency said, forcing evacuations, the closure of a nearby international airport and raising the alert level to its highest.

Ruang, located in Indonesia's outermost region of North Sulawesi province, erupted at around 1715 GMT on Monday and twice more on Tuesday morning, the volcanology agency said in a statement.

It said the volcano sent a tower of ash more than five kilometres into the sky.

Authorities warned tat the threat from the volcano was not over after it erupted more than half a dozen times this month, sparking the evacuation of more than 6,000 people.

The agency also re-instated a six-kilometre exclusion zone.

It said locals should be aware of "the potential for ejections of incandescent rocks, hot clouds and tsunamis due to eruption material entering the sea".

More than 800 people live in Ruang, all of whom were evacuated this month.

Some had returned to their homes after the emergency response status ended on Monday, an AFP news journalist said.

It was unclear how many residents had gone back and how many were forced to evacuate one more.

Ruang's latest eruption also prompted authorities to again close Sam Ratulangi International Airport, according to a notice from state-run air traffic control provider AirNav Indonesia.

The notice said the airport was shutting down due to "Ruang volcanic ash".

The airport in the provincial capital of Manado is more than 100 kilometres away.

Indonesia, a vast archipelago nation, experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire".