The new rules apply to the implementation of Hong Kong's national security law, which was imposed by Beijing in 2020 after huge and sometimes violent pro-democracy protests in the financial hub.

One of the amendments that came into effect on Monday requires people to provide "any password or other decryption method" necessary to allow police to access electronic equipment that is believed to hold evidence.

Anyone who fails to comply faces a year in prison and a fine of HK$100,000 ($12,780).

Previously, refusal to give police a password to unlock a phone or other electronic device did not constitute obstruction.

The new rule applies to people under investigation for endangering national security and people who own or possess the equipment involved, as well as those authorised to access the equipment and anyone who knows the password or decryption method.

They were drawn up by Chief Executive John Lee in conjunction with the National Security Commission.

They are designed to ensure that "activities endangering national security can be effectively prevented, suppressed and punished, and at the same time the lawful rights and interests of individuals and organisations are adequately protected", a government spokesperson said.

Hong Kong imposed its own security law in 2024 in addition to the broader law imposed by Beijing after the 2019 protests.