Xi "expressed deep sorrow" over the destruction and said China was "willing to provide Myanmar the needed assistance to support people in affected areas" in his message of condolence to junta chief Min Aung Hlaing, according to state broadcaster CCTV.

The 7.7 magnitude quake struck northwest of the central Myanmar city of Sagaing on Friday afternoon, followed minutes later by a 6.7 magnitude aftershock.

The quake destroyed buildings, downed bridges and buckled roads across swaths of Myanmar, with severe damage reported in the second-biggest city, Mandalay.

It also hit parts of China's southwestern Yunnan province and Thailand. Authorities said up to 100 workers were trapped after a 30-storey building under construction collapsed in the Thai capital Bangkok.

China sent an 82-person team of rescuers to Myanmar on Saturday, its emergency management ministry said, after Min Aung Hlaing issued an exceptionally rare appeal for international aid.

A separate team from China's Yunnan arrived in Myanmar's commercial hub Yangon on Saturday, CCTV reported.

Four years of civil war in Myanmar sparked by a military coup have ravaged the healthcare and emergency response systems.

Previous military governments have shunned foreign assistance even after major natural disasters.

China's foreign ministry said in a separate statement early on Saturday that there were no reports of casualties among Chinese citizens.