Thousands of travellers have been stranded in Bali after flights were grounded and residents ordered to evacuate as the Mount Agung volcano escalates.

Ash from the volcano’s weekend eruption covered roads, cars and buildings in the northeast of the island, as Indonesian authorities raised the alert to the highest level, warning “a potential eruption could happen anytime”.

Steam and ash rose more than six kilometres into the air, prompting warnings from authorities and dozens of flight cancellations.

Jetstar, Virgin and Qantas advised passengers between 10am and 11am on Monday that all flights were cancelled, with Denpasar Airport closed until 7am on Tuesday (local time).

ABC Indonesia correspondent Adam Harvey reported that 441 flights had been cancelled, affecting 59,000 passengers on Monday alone.

Local authorities on Sunday ordered people to “immediately evacuate” from a 7-kilometre exclusion zone after a second eruption in less than a week.

They then widened the exclusion zone around the crater to 10 kilometres on Monday, resulting in more evacuations, with AAP reporting more than 40,000 people evacuated as of Monday afternoon.

Professor Richard Arculus, of the Research School of Earth Sciences at the Australian National University, said while the activity at this level could continue for several days, he warned it could become far worse.

“The main concern … for the Indonesian authorities and everyone living on the island, is that an increase in the amount of magma in motion will develop, leading to the possibility of a major failure of the volcanic edifice and a catastrophic eruption of the type that occurred at Agung in 1963-64 [which killed around 1100 people].”

#Bali now. Not what you want to see when you arrive at the airport. pic.twitter.com/dIZCbzoN2E

— Adam Harvey (@adharves) November 27, 2017

Australia’s Bureau of Meteorology’s Volcanic Ash Advisory Centre (VACC) in Darwin issued maps showing an ash cloud heading southeast over the neighbouring island of Lombok, away from Bali’s capital, Denpasar, where the main international airport is located.

https://twitter.com/Wolfe321/status/934942685714173954

Travellers have been advised to check with their airline if they are headed to or from Bali.

Agung rises majestically over eastern Bali at a height of just over 3000 metres. When it last erupted in 1963 it killed around 1100 people and razed several villages.

– with agencies