"We wish to raise our deep concerns at the imposition of national security legislation on Hong Kong which undermines 'One Country, Two Systems', and has clear implications for human rights," Britain's ambassador to the United Nations in Geneva, Julian Braithwaite, told the UN Human Rights Council.

"We urge the Chinese and Hong Kong governments to reconsider the imposition of this legislation and to engage Hong Kong's people, institutions and judiciary to prevent further erosion of long-standing rights and freedoms," he said.

Braithwaite spoke on behalf of 27 countries, many of them EU members, as well as Australia, Canada, Japan, New Zealand and Switzerland.

Earlier, Hong Kong leader Carrie Lam addressed the Geneva forum by video message and said that China's national security legislation would fill a "gaping hole" and would not undermine Hong Kong's autonomy.

Braithwaite also urged Chinese authorities to allow UN High Commissioner for Human Rights Michelle Bachelet "meaningful and early access" to its Xinjiang region amid reports of arbitrary detention and widespread surveillance of the mostly-Muslim Uyghur minority.

"High Commissioner, we encourage you to provide regular further information on Hong Kong and Xinjiang in order to safeguard rights and freedoms guaranteed under international law," Braithwaite said.

Activists welcomed the initiative.

"The first statement in four years on China - with more than twice the countries supporting - is an urgently-needed response to voice of victims, and to the need for the High Commissioner to take decisive action to monitor China's attacks on Uyghurs and to stop erosion of rights in Hong Kong," Sarah Brooks of the International Service for Human Rights said in a statement.

Australian Associated Press