BANGKOK (AFP) - A shallow 6.1-magnitude earthquake hit north-western Laos near the Thai border early on Thursday (Nov 21), the United States Geological Survey reported, alarming locals who felt buildings shake as far away as the Thai capital Bangkok.

There were no immediate reports of damage after the quake hit at 6.50am local time, roughly three hours after a 5.7-magnitude earthquake in the same region triggered an immediate suspension to Laos' largest-capacity power plant located near its epicentre.

But shaking could be felt more than 700km away in Bangkok, where Pope Francis is currently on a four-day visit.

"The shaking... was the main shock from a quake in Laos at 6.50am and was felt in northern and north-eastern Thailand and Bangkok and suburbs," said Sophon Chaila, an official at the Thai Meteorological Department.

The department said the quake affected nine provinces in Thailand and there were four lesser aftershocks. It also became a top trending topic on Twitter in Thailand, as locals shared videos of swaying overhead lights and rattling window blinds in office buildings.

"As of now, there is no report of damage," Chaila added.

Residents in the Vietnamese capital Hanoi also felt buildings sway.

"The ceiling lights were shaking quite strongly. I felt dizzy and scared," said Hanoi resident Tran Hoa Phuong, who felt the earthquake in her 27-storey apartment building.

After the first quake, the 1,878-megawatt Hongsa Power Plant - Laos' largest-capacity thermal energy generator - immediately suspended operations according to a statement from the Thai-owned company.

No "fundamental" damages or injuries have been found so far, "merely damages to the external texture of the buildings", it said, adding that Hongsa is expected to take 24 hours to complete its inspection.

Photos shared by Thai media showed portions of the power plant's walls had collapsed, and debris littered its premises.

Nearby Xayaburi dam project, one of Laos' largest hydropower dams, has seen "no impact" so far, and is continuing to generate electricity "as normal", said a statement from CK Power.

Information is slow to trickle out of the closed communist state, and there were similarly no official reports of injuries after the twin quakes hit early on Thursday.

Impoverished Laos has ploughed ahead with ambitious dam-building projects that critics say lack transparency and stringent safety measures.

The cost was laid bare last year when a massive hydropower project collapsed in southern Laos, killing dozens and leaving thousands homeless.

Pope Francis arrived in Bangkok on Wednesday and has a busy agenda on Thursday meeting officials and the Thai king before he leads a mass in the evening.

There was no word from his team on whether he felt the quake.

Powerful earthquakes occasionally strike hard in South-east Asia.

In 2016, a 6.8-magnitude quake struck Myanmar, killing at least three people and damaging temples in the ancient temple town of Bagan.