Tiananmen: 30 Years Of Erasing The Same Day

China is set to mark 30 years since the deadly Tiananmen crackdown with a wall of silence, after arresting activists and tightening internet censorship ahead of the anniversary.

It has become a grim, annual tradition for authorities to round up activists ahead of June 4, as they seek to suppress reminders of the 1989 Tiananmen Square pro-democracy demonstrations - a strictly forbidden topic.

A number of activists have been detained or disappeared again this year, and many popular live-streaming services are scheduled to be down around the anniversary for "technical" reasons.

Wikipedia - whose pages include details about the Tiananmen crackdown -- was blocked from the Chinese internet weeks ago, in all its languages.

The Communist Party has suppressed any discussion of the uprising and its bloody suppression over the years. Its army of online censors erases any articles, memes, hashtags or photos alluding to the protest.

Tight security was already in force on Monday, with authorities preventing journalists from filming, taking photographs, or even entering the square in the centre of Beijing.

One AFP journalist was stopped and told to delete images from a camera, and warned not to do it again without permission from authorities.

In spring 1989, students and workers gathered at Tiananmen Square - the symbolic heart of Chinese power - demanding democratic change and an end to corruption, inspiring protests across the country.

After seven weeks of demonstrations, the government deployed tanks and soldiers who chased and killed demonstrators and onlookers in the streets leading to the square on June 4.

Hundreds - possibly more than 1,000 - were killed. Authorities have still not said what really happened or how many were killed that day. (AFP)