Hong Kong stocks closed lower for a second day on Thursday, as a fresh row between Washington and Beijing over a US bill backing protesters stoked concerns that trade talks could hit a snag and delay the "phase one" deal.

The Hang Seng index fell 1.6% to 26,466.88, while the China Enterprises Index lost 1.6% to 10,450.22.

At close, China's A-shares were trading at a premium of 28.07% over Hong Kong-listed H-shares. The Hong Kong issue is definitely a negative factor in the trade talks, Zhang Yansheng, principal researcher at the state-affiliated think-tank China Center for International Economic Exchanges, said at the Bloomberg forum.