HONG KONG/BEIJING Tens of thousands turned out for a candlelit vigil in Hong Kong on Monday in memory of the bloody crackdown on pro-democracy protesters in and near Beijing's Tiananmen Square in 1989, and China moved to halt Internet searches related to the killings.
The Hong Kong demonstrators massed in a downtown park, holding candles around a June 4 memorial and a replica of the Goddess of Democracy statue that was built in Tiananmen Square before tanks and troops crushed the protests.
"Long live democracy. Never forget June 4," shouted members of a crowd estimated at 180,000 by the event's organisers.
China has never released a death toll, but estimates by human rights groups and witnesses range from several hundred to several thousand. The anniversary has never been publicly marked in mainland China.
Instead, China's censors blocked access to the term "Shanghai stock market" on popular microblogs after the index fell a bizarre 64.89 points, matching the date of the crackdown.
In another twist, the Shanghai Composite Index opened at 2346.98 points on the 23rd anniversary of the killings. The numbers 46.98 are 4 June, 1989, backwards.
"Whoa, these figures are too freaky! Very cool!" said a microblogger. "The opening figure and the drop are both too creepy," said another.
The Shanghai Stock Exchange said it was investigating.
For China's ruling Communist Party, all discussion of the 1989 demonstrations that clogged Tiananmen Square and spread to other cities remains taboo, all the more so this year as the government prepares for a tricky leadership handover.
But for Hong Kong, a former British colony which enjoys wide-ranging autonomy, the June 4 vigil is an annual event.
Terms related to the anniversary, such as "six four" for June 4, were also blocked on Sina Weibo, the most popular of China's Twitter-like microblogging platforms. Users encountered a message that said the search results could not be displayed "due to relevant laws, regulations and policies".
"It's that day again and once more numerous posts are being deleted," wrote a microblogger.
U.S. State Department deputy spokesman Mark Toner urged the Chinese government on Sunday "to provide a full public accounting of those killed, detained or missing".
Chinese Foreign Ministry spokesman Liu Weimin said the U.S. habit of issuing a statement on each June 4 anniversary amounted to "crude meddling in domestic Chinese affairs".
While state media made no direct mention of the anniversary, the top military newspaper ordered the armed forces to be on guard for attempts to sow unrest ahead of the party congress which will handle the change of leadership.
The government is grappling with the biggest political scandal since the 1989 crackdown - the crisis that followed Chongqing police chief Wang Lijun's February 6 flight to the U.S. consulate in Chengdu and toppled Chongqing party chief Bo Xilai.
"I think there is some hope for reform," said Gibson Leung, a Hong Kong resident at the vigil. "There is a much bigger attendance this year, probably because of recent changes in the political atmosphere."
"TRAGEDY ...SHOULD HAVE BEEN AVERTED"
Microbloggers decried the rash of censorship, complaining that their posts had been "harmonised" - a euphemism for censorship - within minutes.
Yet some people did manage to beat the censors, and a few pictures of the 1989 protests did find their way on to Weibo.
"There can be no social stability if people cannot speak out and must live in terror of punishment," one blogger commented.
The government has restricted the movements of dozens of dissidents, former prisoners and petitioners during the anniversary period and ordered them not to speak to journalists or organise activities, said Songlian Wang of rights group Chinese Human Rights Defenders.
A coalition of lawyers and rights activists began a one-day fast in their homes on Monday to mark the anniversary, said Shandong-based lawyer Liu Weiguo.
"Even though the Chinese government has pledged to reform the political system in China, not much has been done," Fang Zheng, who was run over by a tank during the crackdown and lost both legs, said in Hong Kong. "They should stop the repression of mainland dissidents and activists and reassess June 4."
Blind legal activist Chen Guangcheng, who arrived in New York two weeks ago to study, wrote in a letter: "No one can stop the wheels of history. I believe that this will prove true for the June 4 Democracy Movement."
Chinese tourists In Tiananmen Square shook their heads and appeared mystified when asked about the anniversary. There were no obvious signs of extra security In the already well-guarded square.
But a trinket vendor said he was well aware what day it was.
"Do foreigners also know about June 4?" he asked a Reuters reporter in a hushed tone, looking around to make sure nobody heard him. "I think it is important we remember, but nobody will talk about it now."
(Additional reporting by Chris Buckley and Ben Blanchard in Beijing, Melanie Lee in Shanghai,; Sisi Tang and Clarie Lee in Hong Kong; writing by Nick Macfie; editing by Tim Pearce)