WASHINGTON (AFP) - The US, Britain, Australia and Canada released a statement Saturday (Jan 9) underscoring "serious concern" over the mass arrest of Hong Kong democracy figures under a new security law, part of a mounting crackdown by Beijing.

More than 1,000 police officers detained 53 prominent figures - including a US citizen - in dawn raids Wednesday on charges of "subversion," a new national security crime that carries up to life in prison.

The sweep was the latest salvo in Beijing's battle to stamp out dissent in the semi-autonomous city after millions hit the streets in 2019 with huge and sometimes violent democracy protests.

Most of those arrested have since been released.

Western nations have accused Beijing of using its crackdown to shred the freedoms that were promised under the "One Country, Two Systems" setup when the former British colony was returned to China.

Washington has previously sanctioned multiple Chinese and Hong Kong officials, including city leader Carrie Lam. This week US Secretary of State Mike Pompeo said the outgoing Trump administration would consider new sanctions in light of the arrests.

But the new statement from Mr Pompeo and the foreign ministers of the UK, Canada and Australia on Saturday did not mention sanctions.

Instead it stated that they wished to "underscore our serious concern at the mass arrests ... in Hong Kong for subversion under the National Security Law," calling it "a clear breach of the Sino-British Joint Declaration."

"It is clear that the National Security Law is being used to eliminate dissent and opposing political views," it continued.

The foreign ministers called on Hong Kong and Beijing to respect rights and freedoms in Hong Kong, and for delayed local elections to be held "in a fair way that includes candidates representing a range of political opinions."

Hong Kong's 70-seat Legislative Council is only half directly elected, a system that all but guarantees pro-government control.