BALI: Ash spewing from a volcano on Indonesia’s main island of Java has sparked chaos for holidaymakers as airports close and international airlines cancel flights to tourist hotspot Bali, stranding thousands.

Mount Raung in East Java province about 150 km from Bali’s international airport has been rumbling for several weeks. The level of activity increased in the past week and on Friday it blasted ash and debris 3,800 meters into the air.

Government volcanologist Gede Suantika said the eruption forced authorities to close five airports due to the risks posed by volcanic ash, though two airports on Lombok island reopened Friday afternoon. The transport ministry has told airlines to avoid routes near the mountain. It says a decision about reopening other airports will be made by early evening Friday.

Suantika said lava and ash fall from the 3,332-meter-high mountain on Indonesia’s most densely populated island has also resulted in the government calling on people to stay away from a 3 km high-danger zone around the volcano.

Evacuation of residents living near the volcano is still considered unnecessary, but authorities are urging people to wear masks.

Volcanic eruptions can cause significant and lengthy disruption to travel. A 2010 eruption of Iceland’s Eyjafjallajokul volcano produced an ash cloud that caused a week of international aviation chaos, with more than 100,000 flights cancelled.

“Ash can clog engines and harm other parts of the aircraft,” said Transport Ministry spokesman Julius Adravida Barata.

Airports on the islands of Bali and Lombok as well as airports at Banyuwangi and Jember in East Java were closed late Thursday. Barata said thousands of travelers are stranded.

Flights within Indonesia were already overbooked as tens of millions of the country’s Muslims pour out of major cities to return to their villages during an annual mass exodus to celebrate the end of the Islamic holy month.