Sydney  - Australia's north-east coast was on tsunami alert early Thursday after the Pacific Tsunami Warning Centre issued a tsunami warning for Papua New Guinea and island nations in the south- west Pacific following a 8.1-magnitude earthquake which struck off Vanuatu.

The Bureau of Meteorology issued a tsunami watch between Bowen and St Lawrence on the Queensland coast and a tsunami was expected to affect Willis Island off the Queensland coast at about 9:40 am, Australian daylight saving time.

The Great Barrier Reef is expected to act as a protective barrier for areas closer to the Queensland coast.

"It looks like any sort of threat from the tsunami will be getting to the Queensland coast just a little after 12.30 pm and 1 pm around Coolangatta and similar times around the Cooktown area," a bureau official said.

The epicentre of the quake was located 373 kilometres from Vanuatu at a depth of 33 kilometres, the US Geological Survey said.

There were no immediate reports of injuries or damage.

Australian Broadcasting Corporation (ABC) Papua New Guinea correspondent Liam Fox said the quake had not been felt in the capital Port Moresby.

Vanuatu police in the capital, Port Vila, said they had not felt the quake and there were no immediate reports of sea level rises.

A spokesman for New Zealand's Ministry of Civil Defence and Emergency Management said it was issuing a tsunami advisory to keep people off the beaches and warn boats near the coast.

Earlier this morning a magnitude 6.7 quake struck south-east of the Sulu archipelago of the Philippines.

The quake was in the Celebes Sea, 320 kilometres south of Zamboanga in Mindanao, and occurred at 5:41 am local time. The depth was 582.8 kilometres, the USGS said.

In the US, an "expanding regional tsunami warning" was issued for the region near the quake, and there was a "possibility" that Hawaii would be given a watch or warning status, US geological officials said.

The warning comes a week after an undersea 8.3-magnitude quake struck off Samoa, causing a devastating tsunami in Samoa, American Samoa and Tonga, which killed hundreds of people.

A deadly 7.6-magnitude earthquake also hit the Indonesian island of Sumatra, destroying entire villages and buying people alive. The death toll is expected to exceed 1,000. (dpa)