The United States on Wednesday identified 24 more senior Chinese officials it classifies as being instrumental in quashing Hong Kong's freedoms as it warned foreign banks were now banned from doing any business with them.

The decision came shortly before talks were set to begin between senior US and Chinese officials in Alaska -- the first such meeting since President Joe Biden took office -- and Beijing blasted the latest designation.

US relations with China have plunged in recent years over a swathe of issues, including Beijing's crackdown on dissent in Hong Kong after the city was rocked by huge and often violent democracy protests nearly two years ago.

Under the Hong Kong Autonomy Act -- a law enacted last year with bipartisan support -- the State Department has to identify any Chinese and Hong Kong officials involved in eroding the financial hub's freedoms.

The report added two dozen new names bringing the total number listed to 34.

"Foreign financial institutions that knowingly conduct significant transactions with the individuals listed in today's report are now subject to sanctions," Secretary of State Antony Blinken said in a statement.

All those on the list are already subject to sanctions by the Treasury Department or through executive orders from Biden's predecessor Donald Trump. They are mostly top Communist Party officials in Beijing as well as senior national security police officers in Hong Kong.

"This fully exposes the sinister intention of the US to interfere in China's internal affairs, destabilise Hong Kong and obstruct China's stability and development," Chinese foreign ministry spokesperson Zhai Lijian told reporters.

Foreign banks in Hong Kong have been left in quandary over obeying US sanctions as implementing them is illegal under a sweeping national security law imposed by China
Foreign banks in Hong Kong have been left in quandary over obeying US sanctions as implementing them is illegal under a sweeping national security law imposed by China AFP / Anthony WALLACE

Blinken said the expanded list came as Beijing moved last week to "unilaterally undermine Hong Kong's electoral system" by introducing new rules that will effectively stop any real opposition from standing in the city's already limited local elections.

"This action further undermines the high degree of autonomy promised to people in Hong Kong and denies Hong Kongers a voice in their own governance," Blinken said.

Blinken and White House national security adviser Jake Sullivan are set for talks with senior Chinese official Yang Jiechi and Foreign Minister Wang Yi on Thursday in Alaska.

The talks will be the first between the powers since Yang met Blinken's hawkish predecessor Mike Pompeo last June in Hawaii.

The Biden administration has generally backed the tougher approach to China initiated by Trump, but has also insisted that it can be more effective by shoring up alliances and seeking narrow ways to cooperate on priorities such as climate change.

China has reacted with fury to US sanctions over Hong Kong following its imposition last year of a sweeping national security law which outlawed much dissent in the city.

Campaigning for foreign sanctions or implementing them was specifically made illegal under the law, leaving foreign banks in the city facing something of a quandary.

Some of the more than 100 people arrested under the new security law have been accused of advocating for foreign sanctions, including pro-democracy media tycoon Jimmy Lai who is in detention awaiting trial.