More than 4,000 people, led by bookseller Lan Wing-kee, marched in Hong Kong on Saturday, 18 June, to protest against China's detention of five booksellers whose shop published gossipy books about Chinese leaders, including President Xi Jinping.
The demonstration followed a march by 100 activists to China's liaison office on Friday, 17 June, to protest against what they called the "cross-border abductions". They said one bookseller was abducted to China from Hong Kong and another from Thailand.
The protesters' account contradicts official statements that China's law enforcement officials had done nothing illegal. The other booksellers were detained while in mainland China.
The arrest of the five men has prompted fears Beijing may be eroding the "one country, two systems" formula under which Hong Kong has been governed as a special administrative region, since its return to China from British rule in 1997.
Lawmaker Albert Ho said that Lam had risked his life to speak out about what had happened to him.
"Hong Kong people are in fact coming out to sound out our greatest protest against the mainland authority," added Ho, referring to the guaranteed separate laws and freedoms in the former British colony not granted elsewhere in China for 50 years.
Lam told reporters on Thursday 17 June he had been arrested in China and detained for more than eight months but his colleague Lee Bo, a British national, was abducted from Hong Kong by mainland Chinese authorities.
All five men who went missing last year and later appeared in mainland Chinese custody worked at Causeway Bay Books.