Qantas and Virgin Australia have confirmed all their flights to and from Darwin have been cancelled as a massive volcanic ash cloud sweeps from Indonesia towards the Australian mainland.
Flights around Australia may be disrupted by the cloud, which began spreading when Sangeang Api, a volcano off the northeast coast of the Indonesian island of Sumbawa, erupted on Friday evening.
Virgin Australia spokeswoman Jacqui Abbott said all Virgin flights to Darwin on Saturday have been cancelled.
"Because of the impact of the volcano we have cancelled all flights today on our schedule to and from Darwin," she said.
"Our meteorologist aare monitoring the situation and are consulting with the (volcanic ash) advisory centre in Darwin and we will renew normal operations as the situation allows."
Qantas Group spokeswoman Kira Reed said cancellations also affect all Qantas flights to and from Darwin on Saturday and Jetstar's Cairns-Darwin and Darwin-Cairns flights, its Darwin-Adelaide service and its Darwin-Bali, Bali-Darwin, Singapore-Darwin and Darwin-Singapore flights.
The Darwin International Airport website indicates all Saturday flights to and from Darwin have been cancelled.
Volcanic Ash Advisory Centre manager at the Bureau of Meteorology in Darwin, Emile Jansons, said the ash cloud is already affecting Australian air space.
"It has currently reached the Australian coast. It has reached the Kimberley coast (in Western Australia)," he told AAP.
"It is spreading east and it may dissipate, so it is not clear how far east it will get.
"It is not yet clear if it will affect the eastern seaboard."
Mr Jansons said volcanic ash can be hazardous to aircraft but the decision whether or not to fly is a safety and economic decision that rests with individual airlines.
Airports in Singapore and Bali are operating as normal according to a Qantas spokeswoman.