The U.K. has accused the ruling Chinese Communist Party of breaching an international treaty under which the former colony of Hong Kong was handed back to China by removing bookseller Lee Bo, whose "disappearance" alongside four colleagues has been linked to the plans to publish a book about the Chinese president.
In a six-monthly statement to parliament on the implementation of the 1984 Sino-British Joint Declaration under which Hong Kong was handed back to China in 1997, Foreign Secretary Philip Hammond said Lee, a British citizen, was "involuntarily removed" across the internal immigration border to mainland China.
"This constitutes a serious breach of the Sino-British Joint Declaration on Hong Kong and undermines the principle of 'One Country, Two Systems' which assures Hong Kong residents of the protection of the Hong Kong legal system," Hammond said in the statement.
"We have called, in our contacts with the Chinese government at the highest level, for Mr. Lee’s immediate return to Hong Kong," he said.
The statement called on Beijing "to reassure the people of Hong Kong that law enforcement in [Hong Kong] is exclusively the responsibility of the Hong Kong ... authorities, and that the fundamental rights and freedoms of Hong Kong residents will continue to be fully protected," it said.
Causeway Bay Books store manager Lee Bo, 65, was last seen at work on Dec. 30, while four of his associates, publisher Gui Minhai, general manager Lui Bo, and colleagues Cheung Jiping and Lam Wing-kei have gone missing since October.
There is no record of Lee leaving Hong Kong, prompting fears that he was spirited across the internal immigration border by Chinese police, while Gui, who holds a Swedish passport, was apparently detained while on vacation in Thailand.
Gui was later paraded on state-run CCTV in January, "confessing" to having killed a woman in a hit-and-run car accident some years earlier.
Lee has repeatedly said through his wife that he is "assisting in an investigation" at an unknown location in mainland China, amid fears he is being manipulated by police to avoid harsher reprisals.
Repeated calls to Lee's wife Sophie Choi rang unanswered on Friday.
The strongest criticism
The U.K. statement is the strongest criticism of China's detention of the booksellers since they began to go missing last October.
It also throws its support behind the 2014 pro-democracy Occupy Central movement, which campaigned for fully democratic elections, rejecting a plan from the Chinese parliament that would have restricted the choice of candidates to those approved by Beijing.
"The best way to secure the future of 'One Country, Two Systems' is through a transition to universal suffrage which meets the aspirations of the people of Hong Kong," it said.
It said disappearances like Lee's would be less likely with greater political accountability.
"A more democratic and accountable system of government would help strengthen those rights and freedoms which have come under increasing pressure over the past two years," the statement said.
Hong Kong was promised a "high degree of autonomy" in the Joint Declaration and its mini-constitution, the Basic Law, and the maintenance of separate law enforcement, immigration and judicial systems, as well as freedom of expression and association for 50 years after the handover.
The FCO report said high voter turnout rates in district elections last November show that Hong Kong people continue to have a strong appetite for democratic participation in their government, "despite the unsuccessful conclusion of the political reform process."
In June 2014, an unofficial referendum saw 400,000 people vote in favor of universal suffrage and public nominations, despite a central government white paper asserting that the city's autonomy is subject to the will of Beijing.
But just two months later, the NPC published an approved reform plan allowing all of Hong Kong's five million eligible voters to cast ballots in the 2017 race for the next chief executive, but limiting the slate to candidates vetted by Beijing.
It was rejected by pan-democratic lawmakers and protesters at the 79-day Occupy Central, or Umbrella, movement as "fake universal suffrage," because pan-democratic candidates were highly unlikely to be nominated.
Hong Kong's Legislative Council (LegCo) dealt a death blow to the reform package on June 18, 2015, in a humiliating defeat for the city's chief executive Leung Chun-ying and Beijing, voting it down by 28 votes to eight after 34 pro-Beijing lawmakers walked out in an unsuccessful bid to stall the vote.
Reported by Hai Nan for RFA's Cantonese Service. Translated and written in English by Luisetta Mudie.