Volcanic eruptions have continued on mount Shin-moedake in southwestern Japan since early Wednesday.
The mountain in Kyushu straddles Kagoshima and Miyazaki prefectures.
The Meteorological Agency has raised its alert level to 3 on a scale of 1 to 5, restricting approach to the volcano. It is also advising people to be careful of falling cinders and pyroclastic flows within about 2 kilometers of the crater.
The agency says the small-scale eruption started around 5:34 AM. There was a plume of smoke about 300 meters high, and the smoke is increasing.
The agency says tremors from the volcano are increasing, suggesting further volcanic activity. It says it may expand the area of restricted entry in the event of a bigger eruption.
A level 3 warning was last issued for the volcano in October, 2013.