Hong Kong protests: nearly 400 arrested as security law comes in; UK opens pathway to citizenship

Police use water cannon and pepper spray as people take to the streets to protest new security law introduced by China

• Hundreds arrested on first day of new laws
• Boris Johnson says China breaking treaty with UK
• Analysis: security laws usher in new era of control
• How are you affected by protests in Hong Kong?

4.14pm BST

In a Facebook post, Hong Kong police confirmed that they arrested a total of 370 people on various charges, including unlawful assembly, possession of weapons and violating the new security law.

Police said 10 people were arrested under the law, including a man with a Hong Kong independence flag and a woman holding a sign displaying the British flag and calling for Hong Kong's independence all violations of the law that took effect Tuesday night. Others were detained for possessing items advocating independence.

4.04pm BST

Boris Johnson denounced China's imposition of a security law on Hong Kong as a clear and serious" violation of its treaty with Britain, vowing to introduce a bespoke five-year visa for as many as 2.9 million Hong Kong citizens with British national (overseas) status.

Speaking at prime minister's questions on Wednesday he said the law introduced by the Chinese government constituted a clear and serious breach of the Sino-British Joint Declaration, signed in 1984 and aimed at smoothing the transition when the territory was handed back to China in 1997.

Related: China is breaking Hong Kong treaty with UK, says Boris Johnson