Mount Sinabung in Indonesia has erupted sending smoke and ash over four kilometres into the air.

The country's National Disaster Mitigation Agency (BNPB) said no casualties had been reported and that the volcano had been placed on a Level 3 alert – the second-highest level in the graded four-level scale.

This was the first major eruption of Sinabung since February, when it killed at least 16 people believed to have returned home following a period of inactivity.

BNPB spokesman Sutopo Purwo Nugroho said they will be monitoring the volcano: "The public has been informed of this growing [volcanic] activity. The condition is currently still safe, because hot clouds are going in the direction of the Berastepu village, which is still empty [from the previous evacuation]. Ashes are going in the direction of the Sigarang-Garang and Sukanalu villages."

The eruption was not clearly visible due to rain and cloud in the area, but officials observed the volcano with instruments monitoring activity at the site.

According to Indonesia's Antara news agency, there are now 14,382 refugees living in 28 shelters as a result of volcanic activity at Sinabung. "Refugees consists of 13 170 people, in 28 point shelters and 1,212 people in temporary shelters house to rent," an official said in a statement.

Thousands of people living within a three-kilometre radius of the volcano crater have now been living in temporary shelter for almost a year.

People from villages between three and five kilometres have been allowed to return to their homes.

Mount Sinabung began erupting in September last year, with increasing activity until the beginning of February. The most activity was recorded in November, when authorities placed it on the highest alert level.

Before September 2013, it last erupted in 2010, when it killed three people.