The number of people killed in Myanmar following a powerful earthquake has risen to 1,644, with 3,408 others injured, according to local reports.
A further 139 people are also reportedly missing across the country.
It comes as dramatic footage shows the moment a building several stories high collapsed into rubble in the city of Mandalay - near to the earthquake's epicentre.
Survivors in the city dug with their bare hands in a desperate attempt to find trapped people.
It struck at around 12.50pm local time (6.20am UK time) on Friday at a shallow depth of six miles (9.6km).
The quake's epicentre was about 10 miles from Mandalay.
There were also aftershocks, with one measuring a strong 6.4 magnitude 12 minutes later.
King Charles sent a message of condolence.
"I know that the people of Myanmar continue to endure so much hardship and tragedy in your lives, and I have long admired your extraordinary resilience and spirit," he said in a statement.
"At this most difficult and heartbreaking of times, my wife and I send our deepest possible sympathy to all those who have suffered the profound tragedy of losing their loved ones, their homes and their precious livelihoods."
China's President Xi Jinping also sent his condolences to Myanmar's leader Min Aung Hlaing after the earthquake, and, according to the Chinese embassy in Myanmar, they have spoken on the phone.
A Chinese rescue team arrived in Yangon, Myanmar's former capital, early on Saturday, while Russia and the US have also offered to provide humanitarian assistance and relief.
Neighbouring Thailand was also affected by the quake, leaving at least seven people dead, eight injured, and 47 missing.
Buildings in five of Myanmar's cities and towns collapsed, along with a railway bridge and a road bridge on the Yangon-Mandalay Expressway, state media reported. A dam also burst.
The control tower at Nay Pyi Taw airport, which serves the capital Naypyidaw, collapsed, meaning runways cannot be used.
Recalling the moment they left their home in Mandalay, one resident said they "ran out of the house as everything started shaking".
They said they "witnessed a five-storey building collapse in front of [their] eyes", adding, "everyone in my town is out on the road and no one dares to go back inside buildings".
The natural disaster - the largest earthquake in this region in nearly 80 years - comes as the country is in the grip of a civil war.
Search efforts continued on Saturday morning in Bangkok as the city's governor, Chadchart Sittipunt, said people were believed to be alive in the wreckage at three construction sites, including one where a partially built high-rise collapsed.
Most of the city's metro and light rail resumed normal operation on Saturday morning, according to their operators.
Major General Zaw Min Tun, a spokesperson for the military government, told MRTV that blood was in high demand in earthquake-hit areas, as he urged donors to contact hospitals as soon as possible.
United Nations spokesperson Stephane Dujarric said UN staff were working to gather information on the number of people impacted by the earthquake and the scope of the humanitarian needs.
The ruling military junta said a state of emergency has been declared in Sagaing Region, Mandalay Region, Magway Region and northeastern Shan State, Nay Pyi Taw Council Area, and Bago Region.
"The government has ordered a rapid investigation of the damage in these areas," the junta added in a statement.
"We will carry out relief and relief operations promptly. We will also work to provide necessary disaster relief and humanitarian assistance."
The Red Cross has said its attempts to reach Mandalay and Sagaing regions and the southern Shan state are made more challenging by downed power lines.
Image: Buddhist monks walk past a collapsed building in Naypyitaw, Myanmar. Pic: AP Photo/Aung Shine Oo
China will provide 100 million yuan (£10.63m) worth of aid to Myanmar, including tents, blankets, emergency medical kits, food and water.
The first batch is set to arrive on 31 March, according to the Chinese embassy's Facebook page.
