Human Rights Watch chief Kenneth Roth said on Sunday he had been denied entry into Hong Kong, where he had arrived to launch the watchdog's annual report after months of civil unrest in the city.

Hong Kong has been battered by nearly seven months of occasionally violent protests, its biggest political crisis in decades. Millions have turned out on the streets of the semi-autonomous financial hub to demand greater democratic freedoms.

Mr Roth was to give a press conference on Wednesday to unveil his organisation's latest global survey, which accuses China of prosecuting "an intensive attack" on international human rights agencies.

"I had hoped to spotlight Beijing's deepening assault on international efforts to uphold human rights," Mr Roth said. "The refusal to let me enter Hong Kong vividly illustrates the problem."

The long-time executive director of the New York-based rights group said that he was turned back by authorities at the city's airport.

"Even though I've been able to freely enter Hong Kong before, this time, for the first time, they blocked me," he said in a video posted to Twitter.

Still no word from the authorities on why they barred me from entering Hong Kong to release @HRW's annual report which this year highlights the Chinese government's assault on the international human rights system. They could at least own up to the reason. https://t.co/Txiwi28iDh — Kenneth Roth (@KenRoth) January 12, 2020

China last month announced sanctions on American NGOs, including HRW, in retaliation for the passage of a US bill backing Hong Kong's pro-democracy movement.

"These non-governmental organisations support anti-China" forces and "incite separatist activities for Hong Kong independence", China's foreign affairs ministry spokesman Hua Chunying said at the time.

Mr Hua also accused HRW and other groups of having a "great responsibility for the chaotic situation in Hong Kong".

A growing list

The unrest that began last June is the biggest crisis the former British colony has faced since its return to Chinese rule in 1997.

Under the terms of the handover, Hong Kong enjoys unique freedoms unseen on the mainland, but in recent years fears have increased that these liberties are being chipped away as Beijing exerts more control over the territory.

China and the Hong Kong administration have refused to cede to the protesters' demands, which include fully free elections in the city, an inquiry into alleged police misconduct, and amnesty for the nearly 6,500 people arrested during the movement - nearly a third of them under the age of 20.

Mr Roth joins a growing list of openly critical academics, researchers, politicians and activists who have been refused entry in recent years.

Financial Times journalist Victor Mallet was denied a visa renewal without reason in 2018 after he hosted a talk with the leader of a small and now banned independence party at the city's press club.

Last September, an American academic was blocked from entering after he testified in a Congressional hearing alongside prominent Hong Kong democracy activists.