Indonesia's most active volcano has erupted, sending a 6-kilometre column of ash into the sky and triggering the closure of the airport in the nearby city of Solo on Java.

Key points: Villagers living on Merapi's fertile slopes are advised to stay 3km from the crater's mouth

Villagers living on Merapi's fertile slopes are advised to stay 3km from the crater's mouth The eruption lasted almost eight minutes

The eruption lasted almost eight minutes The last major eruption of Mount Merapi, in 2010, killed 353 people

The eruption of Mount Merapi on the main island of Java also unleashed searing gas clouds 2km down its slopes, Indonesia's Geology and Volcanology Research Agency said on its website.

The agency said villagers living on Merapi's fertile slopes were advised to stay 3km from the crater's mouth as the ash made the rain thick and muddy in several villages.

It said the eruption lasted almost eight minutes after it began at 5:22am on Tuesday (local time) and warned of a risk of further eruptions due to continuing movements of magma.

Volcanic ash has engulfed roads in Boyolali, Central Java province. ( Antara Foto/Aloysius Jarot Nugroho via Reuters )

The volcano is a popular site for tourists and its fertile soil is also farmed.

Loading

"Outside a 3km radius it's still safe," Biwara Yuswantana, the head of Yogyakarta's disaster mitigation agency, said.

Yogyakarta city centre is located about 30km from the volcano.

The international airport in Solo was shut at 9:25am (local time), Indonesia's Directorate General of Civil Aviation (DGCA) said. Four flights were affected.

Witnesses said the sound of the eruption was heard 30km away.

The agency did not raise the alert status of Merapi, which was already at the third-highest level due to its ongoing activity.

The 2,968-metre-high mountain is the most active of about 500 Indonesian volcanoes.

The volcano, located near the cities of Yogyakarta and Solo, has rumbled and generated dark hot clouds since last year.

The eruption spewed out a column of ash as well as searing gas clouds along the mountain's slopes. ( AP: Slamet Riyadi )

Its last major eruption, in 2010, killed 353 people.

Indonesia, an archipelago of 240 million people, is prone to earthquakes and volcanic activity because it sits along the Pacific "Ring of Fire", a horseshoe-shaped series of fault lines around the ocean.

ABC/wires