The authorities closed Malang airport for the week on Monday as Mt Bromo shot ash into the sky over East Java, posing a risk to planes, officials said.
The airport, about 25 kilometres west of Bromo, will be closed until December 4, Transport Ministry spokesman Bambang Ervan said.
Bromo, a popular tourist attraction, began rumbling earlier this month and the government has raised the eruption threat warning to the maximum red alert.
“The ash contains chemical substances that could cause engine trouble” to passing planes, Ervan said.
Abdul Rachman Saleh airport in Malang, a city of about 800,000 people, handles 10 daily flights from Jakarta.
Government volcanologist Surono said the volcano was spitting columns of ash some 700 metres into the sky.
“It will continue to erupt in the coming days,” he said.
The country’s most active volcano, Mount Merapi in central Java, has killed more than 320 people in a series of violent eruptions starting late last month.
Unlike Merapi, the countryside around Bromo is not densely populated as it lies within the Bromo-Tengger-Semeru National Park, a huge caldera containing several volcanoes.