A 6.4-magnitude earthquake struck Papua New Guinea on Wednesday, the U.S. Geological Survey said, but no tsunami warning was issued and no damage was immediately reported

The strong quake hit at 09:14 am (2314 GMT Tuesday), 31 kilometers (19 miles) north of Rabaul in the the Pacific nation's east, the USGS said. It was 18 kilometers (11 miles) deep.

Police in Papua New Guinea have detained four men over the gang-rape of a U.S. academic after a massive manhunt, with officials Tuesday urging locals to help find five suspects still on the run.

The American woman said she was was stripped naked, had her hands bound and was raped by the armed mob last week after they tied up her husband and a guide on a jungle trail on Karkar Island in Madang province.

A U.S. academic says she was gang-raped by an armed mob in Papua New Guinea and wants to publicize her ordeal to raise awareness about rampant violence against women in the desperately poor Pacific country.

The attack comes barely a week after an Australian was killed and his friend sexually assaulted by a group of men.

A 6.6-magnitude earthquake shook Papua New Guinea's north Wednesday in a region where a huge tsunami killed more than 2,000 people in 1998, with reports suggesting the area escaped serious damage.

The quake, at a depth of just 13 kilometers (eight miles), hit 23 km east of the small town of Aitape, with a population of around 8,000 on the Pacific nation's north coast, the U.S. Geological Survey said.

A strong 6.6-magnitude earthquake struck off Papua New Guinea on Sunday, the U.S. Geological Survey reported, but a tsunami warning was not issued and no major damage was expected.

The quake hit 105 kilometers (65 miles) west of Panguna, a town on Bougainville Island, at a depth of 64 kilometers, and some 677 kilometers west of the Solomon Islands' capital Honiara, it said.

An international consortium of scientists said on Wednesday they had collected 1.5 million specimens of wildlife in an unprecedented mission to document the biological treasures of Papua New Guinea.

Marine invertebrates, fungus, algae, plants and roughly half a million insects were among the bounty from the three-month exploration of one the world's last biodiversity hotspots, they said at a press conference in Paris.

The U.N.'s rights body on Friday expressed deep concern over the case of a young mother burned alive by a crowd accusing her of sorcery in Papua New Guinea.

"We note with great concern that this case adds to the growing pattern of vigilante attacks and killings of persons accused of sorcery in Papua New Guinea," said Cecile Pouilly, a spokeswoman for the U.N. Office of the High Commissioner for Human Rights.

A United Nations report Monday criticized Australia's immigration camp on Papua New Guinea, warning living conditions are harsh and asylum-seekers' detention arbitrary.

The U.N. High Commissioner for Refugees called for no more children to be sent to the camp on remote Manus Island, which was established as part of Australia's plan to ship refugees offshore to deter more from coming.

A United Nations report Monday criticized Australia's immigration camp on Papua New Guinea, warning living conditions are harsh and asylum-seekers' detention arbitrary.

The U.N. High Commissioner for Refugees called for no more children to be sent to the camp on remote Manus Island, which was established as part of Australia's plan to ship refugees offshore to deter more from coming.

A Polish man was lucky to be alive Friday after sailing from Papua New Guinea to a north Australian island on a raft made of twigs and sticks, through crocodile and shark-infested waters, during a cyclone.

The man was found washed up in mangroves on Saibai Island in the Torres Strait, a treacherous stretch of water that lies between the two countries.