TOKYO, Jan 16 (AFP) - A tsunami caused by a massive underwater volcanic eruption off Tonga has reached Japan's shores, according to the Japan Meteorological Agency.

A 1.2m-high wave was registered at 11.55pm local time on Saturday (Jan 15) at the southern Amami and Tokara islands, where tsunami warnings were issued for waves potentially reaching 3m.

Waves of 1m and below were reported in several areas along the coast, from Hokkaido to Okinawa.

Tsunami advisories were issued for other coastal regions. People in those areas should stay away from beaches and the mouths of rivers, NHK reported.

Japanese broadcaster TBS News said no damage has been reported by the Tokyo Metropolitan Police Department.

The Japan Meteorological Agency had said earlier on Saturday that there was a chance of minor sea-level change but ruled out a damaging tsunami and did not initially issue a warning or advisory, according to The Japan Times.

The US Geological Survey recorded Saturday's eruption as equivalent to a 5.8 magnitude earthquake at zero depth.