Bangkok, June 3 (IANS/EFE): Indonesian authorities evacuated around 6,000 people living on the slopes of Mount Sinabung on Sumatra island, after raising the alert over increased volcanic activity, National Agency for Disaster Management said on Wednesday.

The volume of lava at the top has increased by more than three million cubic metres and was “unstable”, said the agency in a statement.

"There is a risk for the collapse of the dome followed by block-and-ash flows as far as seven km to the south-east," said Sutopo Purwo Nugroho, the agency spokesperson.

In February 2014, 16 people were killed after this volcano erupted, which has been particularly active since September 2010.

Mount Sinabung erupted for the first time in August 2010 after remaining calm for 400 years.

More than 25,000 people had to be evacuated between 2013 and 2014 due to repeated eruptions of lava, rocks and ash.

At least 2,000 of the evacuated people continue to remain in temporary camps.

Indonesia sits on the Ring of Fire in the Pacific Ocean, an area of high seismic and volcanic activity, that is home to more than 400 volcanoes, of which at least 129 are active and 65 are considered dangerous.