Dozens of people were urged to evacuate their homes after a fiery volcanic eruption in southern Japan on Sunday as the national weather agency issued its top-level alert for the mountain.

Television footage showed red-hot rocks and dark plumes exploding from Sakurajima volcano in Kagoshima.

There were no immediate reports of damage, said deputy chief cabinet secretary Yoshihiko Isozaki.

Prime Minister Fumio Kishida has instructed the government "to work closely with the local municipality to ensure damage prevention, such as through evacuations," Isozaki told reporters.

The volcano frequently spits out smoke and ash, and is a major tourist attraction.

Sunday's blast propelled large cinders about 2.5 km from the crater, the Japan Meteorological Agency (JMA) said, while the smoke reached around 300 m and merged with the clouds.

The agency raised its alert for Sakurajima to level five, the top level, which urges evacuations.

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