The Hang Seng Index gained 329.22 points, or 1.66 percent, to open at 20,157.52 points on Tuesday.

Earlier, China's central bank, the People's Bank of China, said it would back major state-backed fund Central Huijin Investment in stabilising the market.

On Monday, stock markets on the mainland, Hong Kong and elsewhere in Asia, sold off sharply on trade war and recession concerns following Washington's imposition of tariffs. (with additional reporting by agencies)