The Hang Seng Index fell by 81.39 points or 0.28 percent at 29,155.40 at the break.
About HK$141.4 billion worth of shares were traded in the morning.
Industrial and Commercial Bank of China (1398) gained by 2.84 percent at HK$5.43, the best performer among blue chips.
Oil shares performed well as crude prices recorded a 13-month high. Cnooc (0883) added 0.33 percent. and PetroChina (0857) won 2.46 percent.
The Hang Seng Tech Index fell by 1.7 percent at 8,669.56.
Alibaba (9988) was up by 0.18 percent, Tencent (0700) dropped by 0.14 percent, Meituan (3690) edged up by 0.06 percent, JD.com (9618) fell by 2.32 percent, and Xiaomi (1810) was down by 3.15 percent.
In mainland China, the Shanghai Stock Exchange Composite Index dropped by 0.34 percent at 3,491.69 points, and the Shenzhen Stock Exchange Composite Index fell by 0.08 percent at 2,296.48.