Scientists sailed yesterday to inspect an undersea volcano that has been erupting for days near Tonga - shooting smoke, steam and ash thousands of meters into the sky above the South Pacific ocean.

"It's a very significant eruption, on quite a large scale," Tonga's geoligical service head, Keleti Mafi, said.

Authorities said yesterday the eruption does not pose any danger to islanders at this stage, and there have been no reports of fish or other animals being affected.