© APIndonesia's National Disaster Mitigation Agency raised the volcano's alert to the highest level Monday and expanded an exclusion zone to 10 kilometers (6 miles) from the crater in places from the previous 7 1/2 kilometers.
Governor Made Pastika said the evacuation period for people living within 10 kilometres of the crater could easily last as long as a month.
Indonesia's disaster management agency said the evacuation is so far orderly and without panic.
Mount Agung has been hurling clouds of white and dark grey ash about 3,000 meters into the atmosphere since the weekend and lava is welling up in the crater, sometimes reflected as a reddish-yellow glow in the ash plumes.
Its explosions can be heard about 12 kilometres away.
Videos released by Indonesia's disaster management agency showed a mudflow of volcanic debris and water - known as a lahar - moving down the volcano's slopes.
It said lahars could increase because it is rainy season and the agency warned people to stay away from rivers.
Spokesman Sutopo Purwo Nugroho told a news conference in Jakarta that the danger zone affects 22 villages and about 90,000 to 100,000 people.
He said about 40,000 people have evacuated but others have not left because they feel safe or don't want to abandon their livestock.
"Authorities will comb the area to persuade them," he said.
About 25,000 people were already living in evacuation centres after an increase in tremors from the mountain in September sparked an evacuation.
Lava rising in the crater "will certainly spill over to the slopes," Mr Sutopo said.
However life continued largely as normal in villages surrounding Agung on Tuesday, with residents setting up traditional markets and offering prayers as the volcano continued to spew tall columns of ash and smoke from its crater.
Mount Agung's last eruption in 1963 killed more than 1,000 people and razed several villages by hurling out pyroclastic material, hot ash, lava and lahar.
Indonesia's Volcanology and Geological Disaster Mitigation Centre warned that if a similar eruption occurred, it could send rocks bigger than fist-size up to 8 kilometres from the summit and volcanic gas a distance of 10 kilometres within three minutes.
Flights grounded again
Bali's Ngurah Rai airport will be closed for a further 24 hours, after being closed on Monday morning due to falling volcanic ash.
The airport said it will reassess the situation on Wednesday morning.
A report from local aviation navigation authorities showed that "aircraft flight channels are covered with volcanic ash", the transportation ministry said in a statement.
Airport spokesman Air Ahsanurrohim said 445 flights were cancelled on Monday, stranding about 59,000 travellers.
Another 30,000 passengers will be unable to leave via plane after today's closure.
Ten alternative airports have been prepared for airlines to divert inbound flights, including in neighbouring provinces.
The airport's closure is having a disruptive effect on flights around Indonesia and the region.
Bali is a hub airport in Indonesia with many flights transiting there for domestic as well as international destinations.
Planes that would have flown other routes on Monday were stuck on the tarmac in Bali.
Human Rights Watch Indonesia researcher Andreas Harsono said he was waiting for two hours at Jakarta's terminal 3 for his delayed flight to a domestic destination.
He said other flight delays had been announced at the terminal, which serves national carrier Garuda, and the departure area was filling up with many waiting passengers.
Indonesia's Directorate General of Land Transportation said 100 buses were being deployed to Bali's international airport and to ferry terminals to help travellers stranded by the eruption.
The agency's chief said major ferry crossing points had been advised to prepare for a surge in passengers and vehicles.
About 500 passengers have so far moved on to airports on the island of Java, but most are remaining on Bali and hoping the airport will resume operations.
Indonesia's Tourism Ministry said member hotels of the Indonesia Hotel and Restaurant Association would provide a night's free accommodation to people affected by the airport closure.
ABC/AP/Reuters
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