A diary which publishers claim is that of the man many blame for the Tiananmen massacre is to be published in Hong Kong.
It gives details on events immediately before and after the killing of workers and students in Beijing in June 1989.
Publishers say the author is Li Peng, the man who announced martial law in Beijing shortly before troops moved in.
In the diary Mr Li declared that he was willing to die to stop the pro-democracy protests.
The news of the diary comes on the 21st anniversary of the massacre.
The book, entitled Li Peng's June 4 Diary, will be published by New Century Press at the end of this month.
The man behind the project is Bao Pu, the son of Bao Tong, a senior advisor to the head of the Chinese Communist Party at the time of the Tiananmen protests.
"It provides amazing details of how decisions were made and how the order was carried out, and how the leaders reached internal consensus," said Bao Pu, talking about the diary.
"These are the kind of things that are not in official records."
It reveals such things as how many troops were involved in the suppression, and where they were deployed.
Who said what in the higher echelons of the party is also detailed in the publication, which will initially appear only in Chinese.
So is the declaration by Li Peng - who was China's premier at the time of the protests - that he was willing to lay down his life.
"From the beginning of the turmoil, I have prepared for the worst," he is quoted as saying in the diaries by Hong Kong's South China Morning Post.
"I would rather sacrifice my own life and that of my family to prevent China from going through a tragedy like the Cultural Revolution," he added, referring to a period of political instability in China from 1966-76.
The manuscript was handed to Mr Bao by an intermediary - he does not want to say who or how it was given to him.
He admits that there are questions about the diary's authenticity, which the publishers say they have worked hard to resolve.
They say they checked facts in the manuscript against material that had already been published. It was also given to various experts to look at.
There are still some doubts, admitted Mr Bao, but they will be published in the book.
He added: "Even with those remaining doubts, I still believe this is authentic, given the details and how consistent they are with other known records."
Mr Bao last year published the memoirs of China's former communist party chief, Zhao Ziyang.
These also covered the 1989 protests, which led to at least hundreds of deaths.
Mr Zhao and Mr Li were great party rivals who had different views on how China should develop.
Mr Zhao was sacked during the pro-democracy protests and remained under house arrest until his death in 2005.
Mr Li, who was never the most popular leader in China, is now 81 and believed to be very ill.
If the diary is authentic, it could be his attempt to justify the actions he and his colleagues took 21 years ago.
There is already a published account of the discussions among China's leaders during the time of the 1989 protests.
The Tiananmen Papers is based on previously secret documents that were leaked by someone whose name has never been revealed.
The Chinese government has not acknowledged their authenticity.