Hong Kong bookseller abduction
Causeway Bay Books employee Lam Wing-kee, after returning from mainland China, attends a news conference in Hong Kong on 16 June 2016Bobby Yip/Reuters

Members of a pro-democracy group are protesting in Honk Kong following revelations that a bookseller has made on his detention in mainland China. Lam Wing-kee was among five booksellers who mysteriously disappeared in 2015.

It later turned out they had been detained by Chinese authorities because of that fact that they worked at the Causeway Bay Bookstore that sold titles criticising the country's leaders.

Lam said he was detained and interrogated for months, and that alleged he and another three detainees were forced to make a confession of "illegal trading".

Some people the men were detained because of a book about President Xi Jinping.

"It was a show, and I accepted it. They gave me the script. I had to follow the script. If I did not follow it strictly, they would ask for a retake," he told a news conference on Thursday (16 June 2016), according to the South China Morning Post.

Following his revelations, dozens of people from pro-democracy groups took to the streets to protest against perceived China's tightening grip on freedom of speech. Associated Press reported that protesters from the Demosisto political party tossed a newspaper, book and petition letter over the Beijing liaison office's fence.

Hong Kong's government said in a statement "The police are now proactively contacting Mr Lam himself to understand more and will take appropriate follow-up action," the BBC has reported.

Hong Kong and China relations

Hong Kong was a British colony until it was given back to China in 1997, with the promise the country would be given autonomy and full freedom in choosing its leaders, under the principle known as 'One Country, Two Systems'.

Hong Kong has accused China of trying to reign in freedom of expression. Relations between China and the the semi-autonomous region have already strained following pro-democracy protests in September 2014, in which thousands of people in Hong Kong took to the streets to rally against China's ruling on the next Hong Kong chief executive election in 2017.

According to Beijing, Hong Kong's potential candidates could be chosen by locals but also have to be vetted by a Chinese nominating committee. The decision enraged thousands of democracy supporters, who fear that China will use the committee to weed out the candidates it disapproves of.