Zhao Ziyang, who died in 2005 after more than 15 years under house arrest, secretly recorded his memories on tapes and passed them on to friends, according to the book´s preface by Adi Ignatius, editor of the Harvard Business Review.
"When Zhao died... some of the people who knew of the recordings launched a complex, clandestine effort to gather the materials in one place and then transcribe them for publication," Ignatius wrote.
In one extract from the book, which could prove embarrassing to China ahead of the 20th anniversary of the Tiananmen crackdown on June 4, Zhao describes his feelings as the army moved in and killed hundreds, possibly thousands.
"On the night of June 3rd, while sitting in the courtyard with my family, I heard intense gunfire," recalled Zhao, who was days away from being deposed as leader of the Communist Party.
"A tragedy to shock the world had not been averted, and was happening after all."
In another passage, Zhao relates a fateful meeting in May 1989 with China´s then leader Deng Xiaoping and other members of the political elite, where the decision to impose martial law was taken, leading to the crackdown.
Zhao says Deng laid the blame for the escalation of student protests on a speech he had made earlier.
"Since there is no way to back down now without the situation spiralling completely out of control, the decision is to move troops into Beijing to impose martial law," he quoted Deng as saying.
"At that moment, I was extremely upset," Zhao said, according to the book, available in Hong Kong but unlikely to legally published in mainland China.
"I told myself that no matter what, I refused to become the general secretary who mobilised the military to crack down on students."
Two days later, Zhao was last seen in public tearfully pleading with students on Tiananmen Square to call off their protests and go home, and one day after that, martial law was publicly declared.
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