The sanctions on Police Commissioner Raymond Siu Chak-yee and the others will block any interests they hold in the United States and generally criminalize financial transactions with them under US law.

The sanctions mark a rare action invoking human rights by the administration of President Donald Trump, who has described China as an adversary but has shown no reluctance to ally with autocrats.

The sanctions "demonstrate the Trump administration's commitment to hold to account those responsible for depriving people in Hong Kong of protected rights and freedoms or who commit acts of transnational repression on US soil or against US persons," Secretary of State Marco Rubio said in a statement.

Other officials targeted in the latest sanctions include Paul Lam, the city's secretary of justice.

Hong Kong's top official, Chief Executive John Lee, is already under US sanctions.

The officials were targeted in line with a US law that champions Hong Kong democracy.

The State Department also pointed to some of the officials' roles in efforts to "intimidate, silence and harass 19 pro-democracy activists" who fled overseas, including one US citizen and four US residents.

Rubio has been outspoken on China's human rights record dating back to his time as a senator.

Rubio earlier also imposed sanctions on officials in Thailand over their deportations back to China of members of the Uyghur minority.

Beijing promised a separate system to Hong Kong when Britain handed over the financial hub in 1997.

China then cracked down hard against dissent, imposing a draconian national security law, after massive and at times destructive protests in favor of democracy swept the city in 2019.