Government spokesman Maj. Gen. Zaw Min Tun told state-run MRTV that another 3,400 have been injured and more than 300 were missing. The military had previously reported 1,644 dead but did not provide specific figures in its update

The 7.7 magnitude earthquake hit at midday Friday, causing widespread damage, including in the capital Naypitaw and the second largest city, Mandalay

Rescue workers at the scene Monday said 70 were able to escape, but 50 have already been found dead and 150 are still unaccounted for

The true number of people killed and injured across the regions hit is thought to be possibly many times the official figures, but with telecommunication outages and extreme challenges to movement around the country, little is known about the damage in many areas

"We're really not clear on the scale of the destruction at this stage," Lauren Ellery, deputy director of programs in Myanmar for the International Rescue Committee, told The Associated Press

There is a state of emergency in six regions, and Ellery said her teams on the ground and their local partners are currently assessing where needs are the greatest, while providing emergency medical care, humanitarian supplies and other assistance

"They were talking about a town near Mandalay where 80 per cent of the buildings were reportedly collapsed, but it wasn't in the news because telecommunications have been slow," she said

The earthquake, centred near Mandalay, a city of some 1.5 million, brought down buildings and damaged other infrastructure like the city's airport

The earthquake also shock neighbouring Thailand and killed at least 18 people, many at a construction site in Bangkok where a partially built high-rise collapsed