Sakurajima, one of Japan's most active volcanoes, erupted before dawn, sending ash and smoke up to 4,400 metres (14,400 feet) into the sky, the Japan Meteorological Agency said.

No damage has been reported, an official in Kagoshima prefecture, where the volcano is located, told AFP.

But the weather agency forecast ashfall in part of Kagoshima and neighbouring Miyazaki prefecture, as the eruption continued several times.

"In areas where a moderate amount of ashfall is expected, please take measures to protect yourself from ash, such as using umbrellas or masks, and make sure to drive slowly," the agency said.

The agency has kept its alert level unchanged at three on a scale of five, which restricts access to the mountain.