Chinese police flood Tiananmen Square to prevent commemoration of military crackdown

Tens of thousands of people were expected to commemorate the anniversary around the world but the only major event on Chinese soil was to take place nearly 2,000 kilometres (1,200 miles) away in semi-autonomous Hong Kong.

On Thursday morning, exactly 20 years after tanks and troops moved in against the student-led protests, hundreds of extra police and plainclothes security personnel were deployed in the central Beijing square, the symbolic heart of political power in China.

Foreign journalists were barred from the area and other visitors were subject to rigorous searches, although the square remained open officially.

The lockdown comes as the authorities try to prevent any event and stifle open discussion marking Thursday's anniversary, fearing that any commemoration could threaten their hold on power.

Hundreds, possibly thousands, died in the massacre, and open debate on the topic is forbidden in mainland China.

In Washington, Secretary of State Hillary Rodham Clinton called on Beijing to publish the names of those killed or missing, saying it would help China “heal.”

“A China that has made enormous progress economically and is emerging to take its rightful place in global leadership should examine openly the darker events of its past,” Mrs. Clinton said in a statement.

She called on Chinese authorities to release all prisoners still serving sentences in connection with the June 4 events, adding, “China can honor the memory of that day by moving to give the rule of law, protection of internationally recognized human rights, and democratic development the same priority as it has given to economic reform.”

China said the US had made "groundless accusations" and expressed its "strong dissatisfaction" with Mrs Clinton's comments.