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."