Two big earthquakes struck Papua New Guinea early Monday but no tsunami warnings were issued and seismologists said while they would have been felt damage was unlikely.

A 7.2 magnitude quake hit the Pacific nation at 4:35 am local time (1835 GMT Sunday), some 110 kilometres (68 miles) northeast of Taron on the island of New Ireland.

It occurred a depth of 379 kilometres (234 miles), the US Geological Survey reported.

This was followed two hours later by a shallower 6.8 quake, 62 kilometres deep near the town of Kandrian on New Britain.

Jonathan Bathgate, a seismologist at GeoScience Australia, said his organisation measured the initial quake at 7.1 and said it was too deep to have caused damage.

"Damage is unlikely although it would have been felt," he said, adding that tsunami warnings were rarely issued for anything more than 100 kilometres in depth.

The second quake was likely an aftershock and while it was on land, Bathgate said the area was too remote for significant damage.

"It would have woken people up but these areas are very remote and the potential is only for minor damage," he said.

Quakes of such magnitude are common in poverty-stricken PNG, which sits on the so-called Pacific "Ring of Fire", a hotspot for seismic activity due to friction between tectonic plates.