Residents in southwestern Japan became increasingly concerned on Thursday as the country's Shinmoedake volcano continued to erupt.

Shinmoedake on Kirishimayama at the prefectural border of Kagoshima and Miyazaki erupted on Wednesday for the first time in about six years.

According to Japanese broadcaster TBS, the plume rose to the height of 1,700 metres from the crater and ash fall was confirmed in the four cities and towns in Miyazaki prefecture with Thursday's eruption.

TBS showed footage of elementary school students wearing helmets and masks on their way to school at the foot of Shinmoedake.

On Wednesday morning, the Japan Meteorological Agency raised the eruption warning level from 2 to 3 on a scale of 5. The agency is warning of big eruptions and pyroclastic flow in the range of 2 kilometres from the crater.