The rebels, led by the Islamist group Hayat Tahrir al-Sham (HTS), captured the central Syrian city of Hama on Thursday, days after seizing the country's commercial hub Aleppo.

They launched their offensive a little more than a week ago, just as a ceasefire took hold between Israel and Assad's ally Hezbollah in Lebanon.

"Currently, the situation in northwestern Syria is intensifying, and the overall security situation is deteriorating further," China's embassy said in a message on its WeChat account on Thursday.

"(The embassy) advises Chinese citizens in the country to make use of available commercial flights to return home or leave the country as soon as possible."

It added that those who remained "may face extremely high security risks and potential delays in receiving assistance".

While Russia and Iran have been Syria's closest backers in recent years, China's ties to the country have grown.

China is one of only a handful of countries outside the Middle East that Assad has visited since Syria's civil war began in 2011.

On that 2023 trip, Chinese President Xi Jinping and Assad announced a "strategic partnership" between their countries.

China's foreign ministry said on Monday that it "supports Syria's efforts to maintain national security and stability" and was "willing to make positive efforts to prevent further deterioration of the situation".