Villagers sit on a truck as they evacuate to a safe spot, as Mount Sinabung spews ash into air at Aman Teran village in Karo district, Indonesia's North Sumatra province, November 24, 2013. The volcano continued to emit volcanic ash, creating an 8,000m (26,247ft) plume of ash, as thousands of residents remain in temporary shelters out of fear for more eruptions , according to local media. [Photo/Agencies]

JAKARTA - Indonesia ordered the evacuation of 15,000 residents near an active volcano in the west of the vast archipelago on Sunday as authorities raised the alert for the emergency to the highest level.

Mount Sinabung on the island of Sumatra has become increasingly active in recent months, spewing columns of ash several km into the air.

Authorities expanded the evacuation radius to 5 km (three miles) from 3 km and the military geared up to move residents out. About 6,000 have already been evacuated from the area, 88 km from Medan, capital of North Sumatra province.

No casualties were reported as the status of the volcano was raised from "standby" to "caution".

"We have raised the status to 'caution', which is the highest of levels for volcanic activity because we anticipate there will be more eruptions and because the intensity of eruptions has been increasing," the National Disaster Mitigation Agency said in a statement.

Sinabung is one of nearly 130 active volcanoes in the world's fourth-most populated country, which straddles the "Pacific Ring of Fire".

The most deadly eruption in recent years was of Mount Merapi in 2010, near the densely populated city of Yogyakarta in central Java. More than 350 people were killed.