Thai King Bhumibol Adulyadej has extended condolence to China over a deadly earthquake in southwest China's Yunnan province, which has left nearly 400 people dead.

Dated August 3, a letter addressed to Chinese President Xi Jinping was posted Monday on the website of the Office of His Majesty's Principal Private Secretary, a royal agency responsible for the royal family's secretarial affairs.

The letter said, "The Queen and I are deeply saddened by the news of the earthquake in Yunnan Province which caused so much loss of lives, casualties and heavy damage to infrastructure and property in your country."

"We wish to extend our sincere and heartfelt condolences to Your Excellency and through you to all those who have suffered loss and bereavement in this natural disaster."

A 6.5-magnitude earthquake jolted Ludian County of Zhaotong City in Yunnan on Sunday, killing at least 398 people and leaving more than 1,800 others injured. Nearly 80,000 houses collapsed and 124,000 others were seriously damaged.