The Hang Seng Index shed 0.4 percent, to 25,524 by lunch.
On the mainland, the Shanghai Composite Index lost 0.4 percent, to 2,892 and the Shenzhen Composite Index slipped 0.2 percent, to 1,596.
Tokyo was down 0.5 percent by lunch. Singapore and Seoul were each down 0.3 percent, Sydney, Taipei and Wellington all dipped 0.1 percent and Manila gave up 0.3 percent.
The pound remained under pressure after Prime Minister Boris Johnson forced an extended suspension of parliament, heightening the prospect of a no-deal Brexit and leading to speculation of a snap no-confidence vote.
It was trading at HK$9.58 and US$1.2205 on Thursday morning. (AFP)
Last updated: 2019-08-29 HKT 13:55