Bali volcano: Mount Agung erupts as airport closure leaves thousands of tourists stranded

The volcano alert for Bali's Mount Agung has been raised to its the highest level, prompting the closure of the tourist island's main airport amid fears of an imminent major eruption.

At least 445 flights were disrupted after the Indonesian volcano belched columns of ash into the sky, leaving 59,000 tourists stranded.

The National Disaster Mitigation Agency said Bali's international airport had closed for 24 hours and authorities would consider reopening it on Tuesday after evaluating the situation.  The small international airport on the neighbouring island of Lombok had already been closed on Sunday after the plumes of ash had drifted east.

"Continuous ash puffs are sometimes accompanied by explosive eruptions accompanied by a weak sound of boom which sounds up to 12 km from thethe summit," the National Board for Disaster Management wrote on Facebook.

"The rays of fire are increasingly observed in at night. This indicates the potential for a larger eruption is imminent."

It said the status of the volcano had consequently been raised from Alert Level 3 to Awas (level 4) and urged people within 10km of the volcano to evacuate. Previously the exclusion zone around the volcano ranged between 6 and 7.5 kilometers.

Geological agency head, Kasbani, who goes by one name, said the alert level was raised at 6 am on Monday because the volcano has shifted from steam-based eruptions to magmatic eruptions. However he said he was still not expecting a major eruption.

"We don't expect a big eruption but we have to stay alert and anticipate," he says.

Indonesian and regional authorities had already heightened flight warnings around Mount Agung on Sunday as the volcano's eruptions sent a plume of volcanic ash and steam more than 6,000 metres into the skies above the popular holiday island.

Ash covered roads, cars and buildings near the volcano in the northeast of the island, while scores of flights were cancelled and overnight a red glow of what appeared to be magma could be seen in photographs by Antara, the state news agency.

Video released by the national disaster agency showed a mudflow of volcanic debris and water known as a lahar moving down the volcano's slopes.

"Watch out for lahar floods (cold lava) around Mt Agung," agency spokesman Sutopo Purwo Nugroho said network Twitter.

"Lahar floods have already occurred in several places on the slopes," he added, referring to expectations of increased rain in the current wet season. He urged people to avoid nearby river areas.

"I'm very concerned because I left my house behind and I'm also worried about family," said 36-year-old farmer Putu Suyasa, who fled with some of his relatives from a village eight kilometres away from the volcano.

National disaster agency spokesman Sutopo Purwo Nugroho called for people to stay calm.

"As we have widened the exclusion zone, so the number of people evacuating will increase but we don't have the latest data yet," he told AFP.

"Most important is always to follow our instructions and keep calm," he added.

Indonesia's Disaster Mitigation Agency said as many as 100,000 villagers needed to leave the expanded danger zone, but that less than half that number had left.

Spokesman Sutopo Purwo Nugroho said about 40,000 people had evacuated but others have not left because they feel safe or don't want to abandon their livestock. He said that "authorities will comb the area to persuade them. If needed, we will forcibly evacuate them."

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.

Agung rises majestically over eastern Bali at a height of just over 3,000 metres. When it last erupted in 1963 it killed more than 1,000 people and razed several villages.

The airport in Bali's capital Denpasar, a top holiday destination that attracts millions of foreign tourists every year, was closed after the threat level was raised on Monday morning.

"Bali's airport has indeed been closed. We're still coordinating the next steps," airport spokesman Arie Ahsanurrohim told AFP.

The closure was set to affect tens of thousands of passengers, he added.

"We now have to find a hotel and spend more of our money that they're not going to cover us for when we get home unfortunately," said Canadian tourist Brandon Olsen who was stranded at Bali's airport with his girlfriend.

"It is a little bit frustrating because I checked the internet..everything was on schedule, now I am standing here everything was closed," said Jan Nicolai from Germany at Bali's airport.

Television footage showed hundreds of holidaymakers camped inside the airport terminal, some sleeping on their bags, others using mobile telephones.

"We have been here (in Bali) for three days we are about to leave today, but just found out our flights have been cancelled. We have got no information because the gates, the check-ins have been closed indefinitely," said Carlo Oben from Los Angeles.

Pictures on social media showed crowds of tourists at the airport, with some passengers on the tarmac at Bali's airport checking their phones and chatting.

According to the Volcanic Ash Advisory Centre in nearby Darwin, Australia, 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.

The airport on Lombok island - also a popular tourist destination east of Bali - had been closed since Sunday afternoon as the ash from Mount Agung headed into that direction, but it reopened early on Monday.

Jetstar Airways announced early on Monday that all Bali flights had been cancelled and a decision would be taken later on Tuesday schedule

After resuming flights on Sunday morning, Virgin Australia again cancelled flights on Sunday afternoon following a change in the aviation colour code from orange to red.

"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," it said on Monday.