Buildings were flattened close to the epicentre while terrified residents fled their homes as tremors were felt as far away as Bangkok, Hanoi and parts of China when the magnitude 6.8 quakes hit late on Thursday.

Myanmar state television confirmed a toll of 74 dead and 111 injured. Nearly 400 homes collapsed in four villages and towns close to the epicentre, the broadcaster said, with nine government offices also destroyed in badly-hit Tarlay town. Several monasteries were also smashed.

Across the border, Thai authorities said a 52-year-old woman was killed in Mae Sai district after a wall in her house collapsed. Sixteen people, including seven Myanmar and five Chinese nationals, were hurt in the quake. In Yangon Chris Herink, Myanmar country director for the charity World Vision said there were reports that the number of people killed had increased.

"The latest unconfirmed number is 140 so it is a worrying trend definitely," he said.

Explaining the high death toll in Myanmar, he said "it's the time of day combined with the severity of the quake and also obviously the construction standards of the homes".

Tarlay, where the hospital collapsed during the quake, was the worst affected township, according to teams in the area.

"As we go further into these areas we see collapsed houses, broken roads, destroyed monasteries and government buildings," he said.

World Vision helps care for around 7,000 children sponsored by overseas donors in the affected areas and the organisation is seeking out those youngsters as a priority.

The charity was able to distribute 1,500 litres of water and food for 1,350 people and Herink said the government had successfully activated its emergency response plans.

A Myanmar official told AFP earlier that "the military, police and local authorities are trying to find some people injured in those affected areas but the roads are still closed".

In Myanmar's fledgling parliament, formed after controversial elections in November last year, legislators put forward a proposal for official condolences to those killed in the quake.

The United Nations Office for the Coordination of Humanitarian Affairs (UNOCHA) issued a report on the situation on Friday.

It said the "risk of landslides remains high" in affected areas and said it had received reports of "sporadic disruption of basic facilities, including electricity, water supply, and telecommunications".

Ben Phillips, of Save the Children in Bangkok, said the organisation was trying to assess the situation in Myanmar. "This is harder as the area affected is more remote. Whilst remoteness may limit the earthquake's impact it also makes it harder to get all the information on impact quickly. It may take days," he said.

Aftershocks continued into Friday following the earthquake. Residents in Chiang Rai city in northern Thailand raced from their homes again in the morning as a large tremor shook the ground.

Four pagodas in the historic town of Chiang Saen near the northern Thai border were damaged, including Chedi Luang, where its three-metre (10-foot) long pinnacle crashed to the ground.

Over 6,000 people were left "stricken" after the earthquake in China's rugged Xishuangbanna border region, but there were no fatalities as of late Thursday night, according to the country's Civil Affairs Ministry

Some residents of the Vietnamese capital Hanoi fled their homes when the quake shook the city, but there were no reported casualties.

Nguyen Thai Son, of the national Global Geophysics Institute's office in northwestern Dien Bien town, 350 kilometres from the epicentre, said "there was big panic among the local residents" but there was no serious damage.

The quake comes two weeks after Japan was hit by a monster earthquake and tsunami that left around 27,000 people dead or missing and triggered a crisis at its Fukushima nuclear plant.

Myanmar and Japan sit on different tectonic plates, separated by the vast Eurasian plate.

No tsunami warning was issued after the Myanmar quake as US seismologists said it was too far inland to generate a devastating wave in the Indian Ocean.

The US Geological Survey (USGS) initially recorded the quake as magnitude 7.0, but later revised it down to 6.8.