Volcano ashes have forced Indonesia to extend the closure of three airports until Saturday, causing travel chaos for thousands of holidaymakers.

Authorities initially said all airports would not be operational until late Friday. However, the Indonesian Transport Ministry later said that the airport in its main tourist hotspot, Bali, and two small airports in East Java would remain closed until at least Saturday morning.

"All three of them will be closed until 10:00 a.m. tomorrow," ministry spokesman J. A. Barata told AFP on Friday, adding, "The air is still not clear."

Authorities closed the airports late Thursday as Mount Raung on Java spewed thick clouds of ash into the sky.

The volcanic activity has coincided with peak season, when tourists flock to the tropical resort.

Crowds of anxious tourists are now stalled in airports awaiting news about their flights.

"There's basically just hundreds of people camped out on the grassy lawns in front of the airport. There's lines of hundreds of people waiting to talk to customer service," said Katie Nagar, an American expatriate, at Bali's Ngurah Rai Airport.

Air traffic is regularly disrupted by volcanic eruptions in Indonesia, which sits on a belt of seismic activity running around the basin of the Pacific Ocean and is home to the highest number of active volcanoes in the world - about 130.