Tourists and locals have been advised to remain outside a two-mile radius of Indonesia’s Mount Merapi, one of the world’s most active volcanoes, following an eruption that sent clouds of grey ash 2,000m into the sky.

Commercial planes have also been warned to take caution in the area while authorities have raised the status of the rumbling volcano to "caution", the second-highest level in Indonesia’s four-tiered alert system.

Falling ash was detected in villages more than six miles south of Merapi, according to a statement by Hanik Humaida, the head of the Geological Disaster Technology Research and Development Centre (BPPTKG).

“There has been an increase in Merapi’s volcanic activity from mid-December 2019 to mid-January this year, both under and on the ground,” Ms Humaida added.

“Similar eruptions can still happen in the future as an indicator that the magma chamber is still supplying magma.”

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Merapi erupted on Thursday at 5.16am local time, lasting 150 seconds in total, Indonesia’s National Disaster Management Agency (BNPB) said.

The Volcanology and Geological Hazard Mitigation Center (PVMBG) has told residents and tourists not to go within 1.86 miles of the volcano, which is located on the border between Central Java and Yogyakarta in Indonesia.

Experts have warned that a collapse of Merapi’s lava dome could cause slides of pyroclastic rocks and other volcanic materials. Concern has also been raised over the possibility of lava floods near the volcano’s slopes during heavy downpours.

Mount Merapi’s last major eruption in 2010 killed more than 300 people and forced the evacuation of some 280,000 residents.

Early last year, a river of lava flowed 4,593 feet down Merapi’s slopes, which authorities dubbed an “effusive eruption phase”.

It is one of more than 120 live volcanoes in Indonesia and has been active since around 1548.