The Hang Seng Index lost 115.32 points, or 0.48 percent, to open at 24,115.98 points on Monday.
In a Fox News interview on Sunday, US President Donald Trump declined to predict whether his tariffs on China, Canada and Mexico would result in a US recession.
Wall Street futures sank and the safe-haven yen and Swiss franc strengthened early on Monday as deflationary pressures in China added to growth worries.
On the mainland, the benchmark Shanghai Composite Index was basically flat at the opening, rising 0.02 percent to 3,373.26 points. The Shenzhen Component Index also opened slightly higher, rising 0.18 percent to10,862.93 points. (with additional reporting from Xinhua and Reuters)