A volcano on Suwanose Island in Kagoshima Prefecture erupted early Monday, the Meteorological Agency has said, warning of the potential for big rocks being hurled into the air within about a 2 kilometer radius of the crater.

The eruption occurred at the crater of Mount Otake at 2:48 a.m., prompting the agency to raise the volcanic activity alert level by one notch to 3 on a scale of 5 to indicate that people should not approach the crater. There were no immediate reports of injuries.

Following the eruption, the government set up a liaison office at the Prime Minister's Office to gather information.

According to the agency, large rocks were thrown to some 1.3 km from the crater and smoke reached about 200 meters above the volcano.

Prior to Monday's eruption, the agency had warned that the volcano had been more active recently, with large rocks thrown nearly 1 km from the crater over the weekend.

Suwanose Island, a volcanic island with small population, is located about 230 km south-southwest of Kagoshima.