Hong Kong's new Chinese history textbooks have for the first time included the Tiananmen Square student protest in Beijing in 1989 but have failed to mention the violent army suppression of it and the fact that students were demonstrating for democracy.
Politicians and educators accused the publishers of distorting history.
None of the five government-approved textbooks about to go on sale for the new senior secondary curriculum which covers Chinese history up to the end of the century mentions the bloody end to the protests or the word democracy.
Estimates of how many died vary from several hundred to thousands.
Cheung Man-kwong, legislator and representative of the Professional Teachers Union, said: "There is no mention of the use of force, that military tanks and machine guns were used to disperse the crowds."
Democratic party leader Martin Lee said: "Are you surprised?" He said that the Chinese Communist Party's United Front would extend its influence over education in the former British colony.
One of the authors of Exploring China History, teacher Chan Hon-sum, admitted to self-censorship. "I should have been more courageous in depicting the event. But as authors, we are all guessing the extent of control the government has over textbooks," he said. He would ask the publisher if he could add references to the military crackdown.
Chief curriculum development officer Lee Chin-hung said the Education and Manpower Bureau set no rules on what should be written in the books.
"For politically sensitive issues, our guideline is they should be presented in a balanced, objective manner, and leave much room for students to form their own views. We cannot issue guidelines for every event in 5,000 years of Chinese history."
Mr Cheung said the teachers' union would issue its own Chinese history teaching materials featuring video footage, the mainland government's version of the event and that by Ding Zilin, founder of the Tiananmen Mothers' advocacy group, whose son was killed.