SYDNEY (Reuters) - A shallow 6.6 magnitude earthquake struck off Papua New Guinea on Monday, the U.S. Geological Survey said, the latest in a series to hit the region in recent days, but there were no immediate reports of casualties or damage.

The quake struck 180 km (110 miles) west of the town of Rabaul, on New Britain island, at a depth of 10 km, the USGS said.

The quake was initially recorded with a magnitude of 7.0 but was later downgraded. There was no immediate tsunami warning.

“We are okay. No one is injured,” said Sylvia Ombul, night desk supervisor at the Kimbe Bay Hotel in the port town of Kimbe, about 140 km to the west of the quake.

“Right now at the hotel all my guests are okay,” Ombul added. She described the quake as “not really big”.

Papua New Guinea, one of the world’s poorest countries, is still reeling a month after a magnitude 7.5 quake hit some 900 km to the west in its rugged and remote highlands, killing at least 100 people as landslides buried villages.