The 7.5 magnitude quake that rocked the region early on Monday also damaged mining and power infrastructure and led ExxonMobil Corp to shut its $19 billion liquefied natural gas (LNG) plant, the country's biggest export earner.

Two buildings collapsed and along with a landslide killed 12 people in Mendi, the provincial capital of the Southern Highlands, said Julie Sakol, a nurse at Mendi General Hospital, where the bodies were brought to the morgue.

"People are afraid. The shaking is still continuing. There's nowhere to go but people are just moving around," she said.

Dozens of aftershocks rattled the area, including a 5.7 quake on Tuesday afternoon, the U.S. Geological Survey reported.

Police in Mendi said 14 people were killed in the initial quake, including three in Poroma, south of Mendi.

Read: Miners Report Some Infrastructure Damage After Papua Quake

"They were killed by landslides destroying families sleeping in their houses," saidNaringBongi, a police officer in Mendi.

Provincial Administrator William Bando said more than 30 people were believed to have been killed in the rugged region, about 560 km (350 miles) northwest of the capital, Port Moresby, the Papua New Guinea Post-Courier reported.

The PNG disaster management office said it was verifying the reports but it could take days to confirm a death toll.

With a lack of communications preventing a clear assessment of damage, aid agencies had not yet begun relief efforts, said Udaya Regmi, head of the International Red Cross in Papua New Guinea, in Port Moresby.

"The magnitude of the earthquake is quite huge, so there must be an impact ... but we cannot say how many people are actually affected and what they need," Regmi said.

ExxonMobil said communications with nearby communities remained down, hampering efforts to assess damage to its facilities that feed the PNG LNG plant.

"Communications continue to be one of the most significant challenges," the company said in an emailed statement.

Its partner, Oil Search, said a review of all of its facilities and infrastructure would take at least a week, and an industry source told Reuters that the Exxon plant will likely be shut at least seven days.

Miners Barrick Gold Corp and Ok Tedi Mining also reported damage to infrastructure.

REUTERS