Indonesia's most active volcano Mount Merapi erupted Monday, belching a cloud of ash into the air as red lava flowed down its crater.

The early morning explosions spewed clouds as far as 3.5 kilometres (2 miles) from the rumbling volcano, blanketing local communities in grey ash.

There were no evacuation orders or reports of casualties.

Merapi, close to Indonesia's cultural capital Yogyakarta on Java island, has been particularly active in recent months and authorities raised its danger level late last year.

Residents were told to avoid the area within a five-kilometre radius of the rumbling volcano, Indonesia's geological agency said.

"Residents should avoid volcanic ash and they've been warned about potential lava flows in the area surrounding Merapi," it added.

Mount Merapi's last major eruption in 2010 killed more than 300 people and forced the evacuation of around 280,000 residents from surrounding areas.

That was its most powerful eruption since 1930, when around 1,300 people were killed, while another explosion in 1994 took about 60 lives.

The Southeast Asian archipelago nation has nearly 130 active volcanoes.

Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire", where tectonic plates collide.