The epicentre of the quake which struck at 1429 GMT was determined to be in waters about 270 kilometres (170 miles) south of Rabaul on the island of New Britain, it said.

It was not immediately known if the quake had caused any damage or injuries.

The Hawaii-based Pacific Tsunami Warning Center said in a bulletin that "no destructive Pacific-wide tsunami threat" exists based on historical earthquake and tsunami date.

But it added: "Earthquakes of this size sometimes generate local tsunamis that can be destructive along coasts located within a hundred kilometres of the earthquake epicentre.

"Authorities in the region should be aware of this possibility and take appropriate action."

An earthquake measuring 6.3 on the Richter Scale struck off the northern coast of Papua New Guinea on Thursday but there were no reports of casualties or damage.

Papua New Guinea sits on the so-called Pacific Rim of Fire, where the meeting of continental plates causes high volcanic and seismic activity.

In July 1998, more than 2,000 people were killed on Papua New Guinea's north coast by a tsunami spawned by an undersea earthquake.

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