SYDNEY - Authorities have been conducting damage assessment and repair work in Papua New Guinea (PNG) after two strong 6.7-magnitude earthquakes jolted the northeastern coast of the Pacific island country during the weekend.

The National Broadcasting Corporation (NBC) of PNG, the country's largest national broadcaster, confirmed on Monday that the National Disaster Office is leading a team of government officials to carry out a comprehensive assessment of the damage caused by the earthquakes and the number of affected people.

At about 6:34 pm local time on Saturday, the United States Geological Survey reported a 6.7-magnitude earthquake hit 56 km southeast of Madang town, the capital of Madang Province in PNG's eastern region.

The epicenter, with a depth of 53.5 km, was initially determined to be at 5.6 degrees south latitude and 146.132 degrees east longitude.

Only minutes later, at approximately 6:40 pm local time, an aftershock of equal magnitude struck beneath the ocean about 52 km southeast of Madang, with the epicenter reaching a depth of 74 km.

Following the two major shocks, PNG has also been rocked by four more tremors, with their magnitudes ranging from 4.4 to 5.7.

The NBC PNG noted that the epicenter was located near Basamuk in the Rai Coast District, a region in the southeast of Madang Province, and the shock was felt in many neighboring provinces, including Morobe, Eastern Highlands, Simbu, and East Sepik.

On Monday, PNG Prime Minister James Marape issued a statement expressing his sympathy and support for the people of Madang and other impacted areas, saying that immediate actions have been taken in response to the tragic disaster.

"Rai Coast Member of Parliament (MP) and Labor and Employment Minister Hon. Kessy Sawang, together with the Madang Provincial Government, have taken swift and decisive action to assess the situation on the ground," said the prime minister.

"A dedicated team comprising officials from relevant government departments and agencies, under the leadership of the National Disaster Office, has been tasked with conducting a comprehensive assessment of the damage and the number of affected individuals," he added.

As MP for Rai Coast, Sawang revealed on her social media that the Basamuk Refinery sustained severe impacts of the earthquakes and ceased production.

"Fortunately, all employees at BSK (Basamuk) are safe, and no environmental spill has been reported so far," she noted.

Meanwhile, according to the latest notice by PNG's state-owned electricity provider, the power supply to most parts of Madang had been restored as of approximately 10:00 am local time on Monday.

The earthquakes plunged the whole province into a total outage since Saturday night, with excessive damages reported to the generator, transmission, and distribution assets of PNG Power.

"We still have areas that have no power, and we can assure you that our teams are working on ensuring they are restored," said the company.

The NBC PNG also updated that flights into Madang airport are likely to be downgraded to Dash 8-300 series and Q400 planes in a bid to allow for urgent repair works to the damaged runway.

PNG Transport and Civil Aviation Minister Walter Schnaubelt was quoted as saying that the earthquakes impaired aerodrome facilities, with long cracks identified along the runway as well as damaged fences.