Flights into and out of the northern Australian city of Darwin were cancelled today and some to Bali disrupted due to huge ash clouds thrown up by an Indonesian volcano.

Indonesia's Sangeang Api volcano began erupting yesterday and its ash is sweeping south towards Australia, prompting Qantas, Jetstar and Virgin Australia to cancel Darwin flights.

"The volcano is continuously erupting," Tim Birch from the Bureau of Meteorology's Volcanic Ash Advisory Centre in Darwin told AFP.

Mr Birch said one plume was affecting northern Australia and impacting Darwin and was expected to linger for at least the next 18 hours.

Another was located over central Australia which could cause problems for overland flights, while a third was about 100km from Denpasar airport on Indonesia's Bali.

"All of the plumes will be affecting aviation," he said.

Surono, an Indonesian government volcanologist who goes by one name, said that Sangeang Api was spewing columns of ash up to 2,500 metres (8,200 feet) into the air.

Virgin Australia cancelled flights to Denpasar airport late today, as did Qantas offshoot Jetstar.

Indonesian flag carrier Garuda cancelled three flights to Denpasar from nearby airports, transport ministry spokesman J. A. Barata told AFP.

However, Denpasar airport reported good visibility and was not itself affected by the ash, he said.

Two small airports close to the volcano in central Indonesia -- one on the island of Sumbawa and another on neighbouring Sumba island -- closed Saturday due to the eruption, Barata said.

The airport on Sumbawa was shut for several hours while the second was due to remain closed until tomorrow.

Australia's Deputy Prime Minister Warren Truss said it could take days for Australian services to return to normal.

Airservices Australia has reportedly begun diverting international flights around the ash plume.

Australian aviation authorities recommend against flights into areas with visible volcanic ash clouds because the fine particles are hazardous to aircraft engines.

A spokeswoman for Darwin International Airport told the Australian Broadcasting Corporation it was not known when flights would resume.

"At this stage it's speculation... from what I can tell, as the ash moves it dissipates so it could be good news for tomorrow," she said.

"But going on past experience, this is usually [a] 24-hour type event."