Britain is considering pulling its judges out of Hong Kong's highest court, Foreign Secretary Dominic Raab said on Monday, in its latest response to what it considers China's breaches of its international obligations in the territory.

Britain, which ruled Hong Kong for over 150 years until it handed it back to China in 1997, says a new security law imposed on the territory by Beijing just before midnight on June 30 was a breach of the 1984 Sino-British Joint Declaration that paved the way for the handover.

London has also objected to new rules imposed by mainland China to disqualify elected legislators in Hong Kong, and to what it describes as retribution by the territory's executive against political opposition and silencing of dissent.