All flights from Australia to Bali have been cancelled because of the ash cloud around Mount Agung.
Indonesian authorities closed Ngurah Rai International Airport in Denpasar on Monday and ordered people within 10 kilometres of the erupting volcano to evacuate after raising the alert to level 4 - the highest level.
The airport said in a statement that 445 flights - 196 international and 249 domestic - and 59,000 passengers had been affected.
Eruptions from Mount Agung have sent volcanic ash and steam up to 4000 metres into the skies above the summit.
"Continuing plumes of smoke are occasionally accompanied by explosive eruptions and the sound of weak blasts that can be heard up to 12 kilometres from the peak," the Disaster Mitigation Agency (BNPB) said in a statement.
"Rays of fire are increasingly visible from night to the following day. This indicates the potential for a larger eruption is imminent," it said.
Jetstar, Virgin Australia and Qantas advised passengers between 10am and 11am on Monday that all flights were cancelled.
The decision was made on safety grounds and overturns earlier expectations that flights would go ahead.
"While these disruptions are frustrating, we will always put safety before schedule," Jetstar said in a statement.
Virgin Australia updated its announcement online saying Denpasar Airport had closed and the airline had subsequently cancelled all flights to Bali.
According to the Australian Bureau of Meteorology's Volcanic Ash Advisory Centre (VAAC) in nearby Darwin, there is "ash confirmed on the ground at Denpasar Airport" as well as ash at "FL300" - which refers to flight level at 30,000 feet - in the vicinity of the volcano.
Airport spokesman Arie Ahsan said the airport closure was based on information from VAAC and the Indonesian Agency for Meteorology, Climatology and Geophysics.
"The ash is very light in the airport buildings but what effects flights would be the thickness in the air," he said.
Buses were being used to get a mixture of Indonesian and foreigner passengers to Padang Bai port and other destinations.
"The authorities will meet every six hours to evaluate the conditions. We can't predict the outcome," he said.
Airlines have set up customer service desks at the international terminal. A Jetstar staff member said that not many passengers had arrived because most already knew that the airport was closed and that there were no flights out. Those who had come had booked through travel agents and didn't know.
Consulates have also set up desks, although there was no sign of an Australian consulate presence.
Agoes Soebagio, an official at the Transportation Ministry, said that Lombok Airport on nearby Lombok island had reopened after an earlier closure, because "no volcanic ash was detected".
The cancellations on Monday come after dozens of flights to and from Bali were scrapped on Sunday after ash from the volcano covered roads, cars and buildings.
Waspadai banjir lahar hujan (lahar dingin) di sekitar Gunung Agung. Banjir lahar hujan sudah terjadi di beberapa tempat di lereng Gunung Agung. Hujan akan meningkat. Jangan melakukan aktivitas di sekitar sungai. Radius 8-10 km harus kosong dari aktivitas masyarakat. #Balipic.twitter.com/5vuZ4KTTYa— Sutopo Purwo Nugroho (@Sutopo_BNPB) November 27, 2017
Volcanic ash poses a potentially deadly threat to aircraft and passengers.
Mount Agung is just over 72 kilometres from Kuta, and towers over eastern Bali at a height of just over 3000 metres.
It last erupted in 1963, killing more than 1000 people and razing several villages.
Bali, famous for its surf, beaches and temples, attracted nearly 5 million visitors last year but business has slumped in areas around the volcano since September when Agung's volcanic tremors began to increase.
with AAP, Reuters