IT WAS 25 years ago today that Chinese troops killed thousands of pro-democracy protesters at Tiananmen Square.

Beijing put extra police on the streets today and detained government critics as part of a security crackdown for the 25th anniversary.

Tens of thousands of people came out to mark the anniversary.

Student demonstrators waved pro-Taiwan independence flags at Liberty Square in Taipei, Taiwan.

AP / Press Association Images AP / Press Association Images / Press Association Images

Heavy security blanketed central Beijing pre-empting any attempts to publicly commemorate one of the darkest chapters in recent Chinese history.

Paramilitary policemen marched on Tiananmen Square after a flag-lowering ceremony on Tiananmen Square.

Alexander F. Yuan Alexander F. Yuan

A paramilitary policeman in plain clothes with an umbrella, center, looks back as his uniformed comrade while he holds his position during a flag-lowering ceremony on Tiananmen Square in Beijing.

Alexander F. Yuan Alexander F. Yuan

Even now a quarter of a century after the Communist Party’’s attack on demonstrations, the ruling party prohibits public discussion and 1989 is banned from textbooks and Chinese websites.

These photo’s show Beijing then and now, 25 years on: