by SALLY RAWSTHORNE
FLIGHTS in and out of Bali have been further delayed after authorities this morning increased Mount Agung's threat level to the highest possible and increased the exclusion zone around the mountain.
The alert level was today upgraded from three to four, the highest on the scale, as magma is now believed to close to the crater.
And Indonesia's Volcano Observatory Notice for Aviation (VONA) extended the exclusion zone from 7.5km to 8-10km with warnings for everyone to remain outside the zone with the likelihood of a major eruption now increasing.
Denpasar Airport has been closed due to the ash cloud until 7am local time, 10am AEDT, tomorrow.
"While these disruptions are frustrating, we will always put safety before schedule," Jetstar said in a statement.
Due to the significant volcanic ash and current weather conditions, Denpasar Airport is now closed and we have cancelled today's flights to and from Bali," Virgin Australia said.
The National Disaster Mitigation Agency said Bali's international airport had closed for 24 hours and authorities would consider reopening it Tuesday after evaluating the situation.
Geological agency head, Kasbani, who goes by one name, said the alert level was raised at 6 a.m. on Monday because the volcano has shifted from steam-based eruptions to magmatic eruptions. However he says he's still not expecting a major eruption.
"We don't expect a big eruption but we have to stay alert and anticipate," he said
The nearby airport, on Lombok, has been closed, as the ash cloud drifts in that direction.
Mt Agung started erupting last week after first rumbling into action back in September, forcing thousands of villagers who live on its slopes and in its shadow, into temporary shelters.
- Cindy Wockner and wires
Schoolies chaos after volcano erupts
A SIX and a half-hour flight from Sydney to Bali turned into a 25 hour nightmare for dozens of Schoolies bound for the Indonesian island when Mount Agung erupted.
Jetstar flight JQ37 left Sydney on Saturday evening, but was forced to turn around 90 minutes short of Denpasar Airport because of ash and smoke spewing from the volcano.
The Jetstar plane's 320 passengers were taken to Darwin, then flown to Cairns because the Northern Territory capital had no accommodation.
While in Darwin, four men en route for Schoolies were removed from the plane by the Australian Federal Police because of their rowdiness.
It's understood the men have gone on to fly to Bali.
Flights from Sydney, Adelaide, Townsville, Perth and Melbourne to Bali on the budget carrier were all cancelled yesterday.
"It's a safety decision. Volcanic ash can cause damage to the engine, so if there's volcanic ash in the area we won't fly," a spokesman said when asked why Jetstar would not fly there when other airlines continued to.
The passengers from Sydney were forced to spend the night at the Cairns airport terminal, with some returning to Sydney on Sunday afternoon, some remaining in North Queensland and others being diverted to Melbourne - all hoping to make it to Bali to celebrate the end of their education.
"We had been on the plane for five hours, and we got turned around to Darwin and we just sat on the runway for two hours," Rosie Buman, 18, told The Daily Telegraph at Sydney airport on Sunday afternoon.
She and nine friends from St Clare's College Waverley had been planning a trip to Bali for the entire year, with each girl paying $800 for a villa in Seminyak for a week.
"There were 180 seats on the plane out of Cairns. They said the rest of us would just have to wait for tomorrow," she added.
Three of Buman's friends were able to return to Sydney, where they hope to fly to Bali from immediately, but six were diverted to Melbourne.
On Sunday, Jetstar resumed flights back to Bali but acknowledged not all of their passengers would be able to fly straight away.
Ash rises as Mr Agung erupts
"There are limited available seats on today's flights.
"We will be moving as many customers from yesterday's cancelled flights as we can," the airline said in a statement.
Mount Agung erupted in September, causing 140,000 local Balinese residents to evacuate.
This week, it has exhaled smoke up to 1,500 metres above its 3,000 metre summit.