The magnitude 7.5 quake rocked the rugged Southern Highlands province some 560 km northwest of the capital, Port Moresby, triggering landslides, damaging mining, gas and power infrastructure, and cutting communications.

Scores of aftershocks have hampered rescue efforts and rattled nervous villagers over the past two days, including a 6.0 tremor just before 1 pm local time registered by the US Geological Survey.

Most of the confirmed fatalities were in or around the provincial capital of Mendi and the town of Tari, according to authorities and residents contacted by Reuters.

"It's massive destruction," Stanley Mamu told Reuters by telephone from Tari, 40 km from the epicentre. One person was killed in Tari and another five were killed in a landslide in a nearby village, he said.

Australia has sent a C-130 military transport plane to help with aerial surveillance.

Miners and oil and gas companies are also assessing the damage, which includes ensuring a 700-km gas pipeline that connects to a coastal liquefaction plant is intact.d.

A police officer in Mendi said landslides had buried homes and blocked a river residents worried could flood the town.

"We are really in deep fear," said police sergeant Naring Bongi. "It continues to be active. We didn't sleep well and stayed awake until daybreak ... no helicopters or government officials have come to our assistance."

Medical supplies, food and heavy equipment to clear landslides were also needed, said James Justin, a spokesman for provincial MP Manasseh Makiba.

"The casualties have yet to be confirmed but many more than 20 people have lost their lives," he said.

Australian Associated Press