Bali’s international airport has reopened following an eruption of ash from the island’s Mount Agung volcano but travellers have been told it could be days before they are booked on another flight.

More than 8000 people were left stranded in Bali when Denpasar Airport was closed on Friday following the eruption which sent a column of ash two kilometres into the air.

As many as 48 flights leaving Denpasar Airport were cancelled, including 38 international flights and 10 domestic flights.

On Friday evening, Jetstar and Qantas announced they were resuming flights but warned there would be further delays as they dealt with a large backlog of customers.

“Volcanic activity is unpredictable, so please be aware that conditions can change rapidly,” a Jetstar spokesman said. “We will update you immediately if there is any change to our schedule.”

Trying to leave Denpasar airport after #MountAgung’s eruption closed the airport for most of the day. Easily 1,000 waiting in line and the luggage belts seemed to have failed. #Balivolcano pic.twitter.com/em0FPDpI7Z

— Matilda Boseley (@MatildaBoseley) June 29, 2018

“Please bear in mind there is a backlog of customers waiting to fly so it may take several days before you are booked on a flight.”

Flights in Australia bound for Denpasar on Friday were also cancelled after the Volcanic Ash Advisory Centre determined conditions “remain unsuitable for flying”.

Another passenger described the “mayhem” inside the terminal.

https://twitter.com/J4yJay/status/1012885157454348289

The volcano’s alert level remained high on Friday.

Virgin cancelled two flights between Sydney and Denpasar on Thursday and Friday’s flights were cancelled.

“We understand that these cancellations are frustrating and our number one priority is to have guests on their way as soon as it is safe to do so,” the airline said in a statement.

The disruptions come as almost half of Australia’s schoolchildren prepare to embark on their mid-year holidays.

More than 20 flights across Jetstar, Qantas, Virgin and Air Asia were disrupted between Thursday night and throughout Friday, with passengers encouraged to check airlines’ websites.

The Mount Agung volcano sent an ash column of 2500 metres into the air and a red flame was visible in Mount Agung’s crater, Sutopo Purwo Nugroho, according to a disaster mitigation agency.

Air Asia cancelled three flights between Perth and Bali, and a Denpasar to Perth flight amid fears the ash could affect the aircraft engines.

Mount Agung has awoken! pic.twitter.com/vGkx0V2c8r

— Roxanne Taylor Media (@Roxanne_Taylor) June 28, 2018

It said 26 international inbound and outbound flights had been cancelled, affecting nearly 5000 travellers, while some 10 domestic flights were cancelled, affecting more than 1700 passengers.

Jetstar flights going to Denpasar from Sydney, Perth, Melbourne, Adelaide and Cairns were also turned back on Thursday night, with the company releasing a travel alert statement on their website.

“Due to a volcanic ash cloud caused by Mount Agung in Bali, it is currently not safe to operate flights to or from Denpasar Airport,” it read.

Qantas also turned back two Melbourne and Sydney flights on their way to the island, and delayed two more due to depart Denpasar.

Students in Victoria, Queensland, Western Australia and the Northern Territory begin school holidays from Friday afternoon, with their New South Wales, South Australian, Tasmanian and ACT counterparts joining them next week.

In November last year, holiday goers were left stranded after Mount Agung hurled clouds of ash 3000 metres into the atmosphere, closing the island’s main airport.

Mount Agung is about 70km northeast of Bali’s tourist hotspot of Kuta.

It’s last major eruption was in 1963 and killed about 1200 people.

Activity at the volcano was high last year and forced the evacuation of tens of thousands of people, but it had been quieter this year.

Indonesia, an archipelago of more than 250 million people, sits on the Pacific “Ring of Fire” and is prone to earthquakes and volcanic eruptions.

Local government seismologists monitor more than 120 active volcanoes.

-with AAP