A volcano which has erupted in Papua New Guinea was Saturday spewing fragments from its crater and rumbling loudly, but its activity appeared to be subsiding, a seismologist said.

Mount Tavurvur, which destroyed the town of Rabaul when it erupted simultaneously with nearby Mount Vulcan in 1994, came to life again early Friday, with rocks and ash erupting from its centre.

The eruptions on the remote island of New Britain in eastern PNG thrust plumes of ash into the air, prompting local evacuations and international flights to modify their routes.

"At the moment we are getting only discrete explosions," Jonathan Kuduon, a senior seismologist at the Rabaul Volcanological Observatory, told AFP.

"The activity has subsided," he said, adding that the fragments were reaching less than 200 metres (600 feet) above the crater.

"These small explosions are usually accompanied by noise."

So far there have been no reports of injuries or damage, but the volcano continued to boom and spew lava overnight and parts of Rabaul are blanketed in ash and pumice stone.

Kuduon said Mount Tavurvur remained a concern, saying officials were worried about the amount of ash in parts of Rabaul, but the kind of eruption -- Strombolian (low-level) -- meant it could subside quickly.

"I think from Tavurvur you can expect small eruptions to go on yet. You can still expect eruptions from that volcano but not from Vulcan," he said.

"Looking at past eruptions, I think the eruptions are getting less and less. Which simply means that the volcano is dying out."

The Volcanic Ash Advisory Centre in the northern Australian city of Darwin said it was keeping a close eye on the situation after Friday's eruption which saw ash reach 60,000 feet (18,000 metres) which is flight level.

"The last two big eruptions at Rabaul, you've had the Tavurvur eruptions first and then one in a fairly close time period you've had Vulcan erupt," official Cyndee Seals told AFP.

But Kuduon said he was not overly concerned about Mount Vulcan erupting.

This crater rumbled to life with Tavurvur in 1994, with the eruptions destroying much of Rabaul, with falling ash causing buildings to collapse. While loss of life was minimal, looters ransacked the evacuated town.

"In 1994 you had eruptions from Vulcan that went (on) for nearly two weeks and then the volcano just shut of," Kuduon said.

The seismologist said the people of Rabaul were now waiting for the eruptions from the 688-metre (2,270-foot) Tavurvur crater to stop completely.

"We need to go back to our normal life. So long as we have eruptions going it will affect our normal life. We only wish that the volcano can go back to sleep now," he said.

PNG sits on the Pacific "Ring of Fire" where high volcanic and seismic activity is the norm.

The Post-Courier reported that Rabaul port was temporarily closed Friday as a precautionary measure.