Indonesian authorities began evacuating people living on the volatile Mount Merapi volcano’s fertile slopes on Friday following an increase in volcanic activity.

The head of Yogyakarta’s Volcanology and Geological Hazard Mitigation Centre, Hanik Humaida, warned that Merapi, Indonesia’s most active volcano, could erupt at any time, possibly sending hot gas clouds down its slopes up to three miles.

Edy Susanto, a local disaster mitigation agency official, said about 300 people from two villages, mostly the elderly, pregnant women and children, were taken to emergency shelters in Central Java’s Magelang district.

Mr Susanto said emergency measures to evacuate people living within 3.7 miles of the crater’s mouth were being prepared as local administrations in Central Java and Yogyakarta provinces closely monitor the situation.

On Thursday, Indonesia’s geological agency raised Merapi’s alert level to the second-highest level after sensors picked up increased activity.

The 9,737-foot mountain is about 18 miles from the Yogyakarta city centre.

About a quarter million people live within a six-mile radius of the volcano.

Merapi spewed ash and hot gas in a column as high as 3.7 miles into the sky in June, but no casualties were reported.

Its last major eruption in 2010 killed 347 people and caused the evacuation of 20,000 villagers.

Indonesia, an archipelago of more than 270 million people, sits on the Pacific Ring of Fire and is prone to earthquakes and volcanic eruptions.

Government seismologists monitor more than 120 active volcanoes.