JAKARTA - Authorities have begun evacuating 3,000 residents near the Mount Ibu volcano on Indonesia's eastern island of Halmahera, the disaster agency said on Thursday, after an eruption this week sent a cloud of thick grey ash as high as four-km (2.5-mile) into the sky.

Ibu erupted on Wednesday morning for about two minutes, Indonesia's volcanology agency said, forcing authorities to raise the alert level in the surrounding areas to the most severe.

ALSO READ: Indonesia's Mt Ibu volcano erupts, spewing clouds of ash

The evacuations started late on Wednesday for about 3,000 residents around the area who were being prioritised due to their proximity to the volcano, Abdul Muhari, a spokesperson for the country's disaster mitigation agency, told Reuters.

He had previously said 13,000 people were living near the volcano.

"Judging from the situation from the ground, it is still pretty stable," he said.

READ MORE: Indonesia's Ibu volcano erupts twice, spewing red-hot lava

Ibu's activities follow a series of eruptions of different volcanoes in Indonesia, which sits on the Pacific "Ring of Fire" and has 127 active volcanoes.

Ibu had a series of eruptions last year. In May, it had forced the evacuation of people living in seven nearby villages.