HONG KONG: China opened a new office on Wednesday for its intelligence agents to operate openly in Hong Kong for the first time under a tough new security law, in a public display of its tightening control over the finance hub.

The new base is located in a rapidly converted hotel overlooking the city's Victoria Park, a location that has hosted pro-democracy protests for years, including an annual vigil marking Beijing's deadly Tiananmen crackdown.

A plaque bearing the security agency's name was unveiled early Wednesday in front of Hong Kong government and mainland officials - including Beijing's top envoy to the city and the commander of the Chinese army barracks in Hong Kong. Police blocked roads around the former Metropark Hotel and surrounded it with water-filled barriers. A Chinese flag was unfurled on a pole erected outside the building while a plaque with the national emblem went up overnight.

City leader Carrie Lam - a pro-Beijing appointee - hailed the opening as "a historic moment" and said China's intelligence apparatus would be an "important partner" in helping to safeguard national security.

Luo Huining, Beijing's top envoy to Hong Kong, said the city had "bade farewell to the days when it was defenceless in national security".