China has expressed "strong dissatisfaction" over a statement issued by the US calling for the release of prisoners still detained over the 1989 Tiananmen Square protests in Beijing.
The response from China's foreign ministry on Monday came on the 23rd anniversary of the quashing of pro-democracy demonstrations by the Chinese military in which hundreds of protesters are estimated to have been killed.
The US statement, issued by the Department of State, called on Beijing to "provide a full public accounting of those killed, detained or missing; and to end the continued harassment of demonstration participants and their families."
- Terms like "six four", "23", "candle" and "never forget" blocked on the internet
- Posts on microblogging sites "harmonised" - a euphemism for censorship
- Censors also prevent microbloggers from changing their display photos in an attempt to prevent them from posting any anniversary pictures
"We renew our call for China to protect the universal human rights of all its citizens; release those who have been wrongfully detained, prosecuted, incarcerated, forcibly disappeared, or placed under house arrest; and end the ongoing harassment of human rights activists and their families," said the statement, issued by Mark Toner, the Department of State's deputy spokesman.
The 1989 pro-democracy demonstrations in China gained international coverage, with an image of a lone protester obstructing a column of tanks, bringing the protests to the attention of the world at a time when citizens of the Soviet Union and Communist countries in eastern Europe were gaining greater freedoms.
But on June 4 the Chinese military dispersed the protesters using tanks and live ammunition. No official toll has been provided, but estimates range from hundreds to more than 1,000 killed, with up to 10,000 injured and thousands detained.
Beijing still considers the protests a "counter revolutionary rebellion" and has refused to acknowledge any wrongdoing or consider compensation for those killed.
In a rare departure from the official communist party line, mayor of Beijing at the time of the crackdown has described the bloodshed as "regrettable" and "a tragedy that could have been prevented", London-based Financial Times newspaper reported.
Chen Xitong, now 81, is the first time a senior official associated with the decision to fire on protesters has expressed regret for the incident.
"As the mayor, I felt sorry. I hoped we could have solved the case peacefully," Chen is quoted as saying in a book to be published on the eve of the anniversary of the brutal crackdown.
Al Jazeera’s Steve Chao, reporting from Hong Kong, said: "Hong Kong is the only place on Chinese soil where the anniversary can be openly remembered."
"We understand 150,000 people, according to organisers, are set to gather in the evening to remember the June 4 crackdown," he said.
"In recent days a number of activists, who tried to hold their own commemoration, have been harassed and detained and in some cases faced house arrest."
Crackdown on protesters
Authorities in China have blocked internet access to terms such as "six four", "23", "candle" and "never forget", broadening extensive efforts to silence online chatter about the anniversary.
The effect of censorship appeared on Sina Weibo, the most popular of China's Twitter-like microblogging platforms, where users encountered a message that said the banned search results could not be displayed "due to relevant laws, regulations and policies".
Microbloggers decried the overzealous rash of censorship, complaining that their posts had been "harmonised" - a euphemism for censorship - within minutes.
Censors also prevented microbloggers from changing their display photos in an apparent attempt to prevent them from posting any photo commemorating the anniversary.
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Rights campaigners said on Monday that Chinese authorities have rounded up hundreds of activists in the capital Beijing.
Officers used violence against activists in the southeast province of Fujian and detained them, while more than 30 people who came to Beijing "to petition" were held and forced to return to their home province, the activists reported.
"Around 20 rights defenders were stopped by police and beaten this morning on May First Square," Shi Liping, the wife of activist Lin Bingxing, told AFP by phone from Fuzhou, capital of Fujian province.
"The police said they were going to 'beat them to death'. They took about eight people into custody, including my husband. I fear he has been beaten badly."
Police in Fuzhou contacted by AFP denied anyone had been detained.
Any mention of the 1989 protests is banned in state media and the subject is largely taboo in China.
But an overseas dissident website, www.molihua.org , in recent days urged those opposed to the crackdown to dress in black and "stroll" in public places throughout China on June 3-4.
The call, which spread through numerous microblogs, was similar to ones last year urging Chinese to hold protests akin to those that spread through the Arab world.
Veteran dissident Hu Jia said on his microblog that, as in previous years on June 3-4, police had stepped up security around the homes of numerous political activists and social critics in Beijing.
Rights activists and lawyers said police had also contacted them and warned against participating in activities marking the crackdown.
Al Jazeera English is unable to report from Beijing after Chinese authorities refused to renew correspondent Melissa Chan's press credentials and visa, or allow a replacement journalist into the country.