Mount Io, which has erupted for the first time since 1768, may become more active, volcanologist Makoto Saito warns

A volcano in southern Japan erupted for the first time in 250 years on Thursday, spewing steam and ash hundreds of metres into the air, as authorities warned locals not to approach the mountain.

"There is a possibility that (Mount Io) will become more active," said Makoto Saito, an official from the Japan Meteorological Agency (JMA), confirming the eruption.

In a televised press conference, he warned residents in the area to stay away from the , part of the Mount Kirishima group of volcanoes, as major ash deposits spread from the crater.

It was the first eruption of the mountain since 1768, the JMA said.

The agency warned that large flying rocks could fall over a three-kilometre (two-mile) radius.

The eruption threw smoke and ash 400 metres (1,300 feet) into the air.

Footage captured by the JMA and local media showed thick white and grey smoke rising from several areas of the mountain.

There were no immediate reports of injuries, Chief Cabinet Secretary Yoshihide Suga said, adding that the government was "taking all possible measures" to prevent damage and casualties.

The eruption occurred a few kilometres (miles) away from Shinmoedake, which featured in the 1967 James Bond film "You Only Live Twice" and erupted in March.

In this April 19, 2018, photo, volcanic smoke billows from Mt. Io, foreground, part of the Kirishima mountain range on Japan's southern main island of Kyushu, taken over Ebino city, Miyazaki prefecture. The Meteorological Agency said Friday, April 20, 2018 that Mt. Io erupted for the first time since 1768, spewing smoke and ash high into the sky. The agency has expanded a no-go zone to the entire mountain from just around the volcano's crater. At back is Shinmoedake volcano. (Kyodo News via AP)

Japan, with scores of active volcanoes, sits on the so-called Pacific "Ring of Fire" where a large proportion of the world's earthquakes and volcanic eruptions are recorded.

In January, a Japanese soldier was killed and several other people injured after an eruption near a popular ski resort in northwest of Tokyo.

On September 27, 2014, Japan suffered its deadliest eruption in almost 90 years when Mount Ontake, in central Nagano prefecture, burst unexpectedly to life.

An estimated 63 people were killed in the shock which occurred as the peak was packed with hikers out to see the region's spectacular autumn colours.