Tiananmen anniversary: Calls for truth 24 years on
4 June 2013 Last updated at 00:26 BST
The fourth of June is the 24th anniversary of the military crackdown on pro-democracy protesters in China in Tiananmen Square.
Estimates of the death toll range from several hundred to several thousand.
But although for more than two decades the government has never fully disclosed what happened, calls for more openness are increasing.
The BBC's John Sudworth reports from Shanghai.