Activist Nathan Law, one of the most prominent student leaders of the Hong Kong pro-democracy movement and leader of the Demosisto political party, has left the former British colony for an unknown destination, he said on social media Friday.

"Hi this is Nathan. I have already left Hong Kong and continue the advocacy work on the international level. Based on risk assessment, I shall not reveal too much about my personal whereabouts and situation now," Law told journalists in a message on a Whatsapp group.