The diary details how the inner circle of the Communist Party leadership remained sharply divided on how to handle the student protests.

It discusses Li's open differences with deposed party general secretary Zhao Ziyang , his direct involvement in pushing for action against the protesters, and the explicit role of late paramount leader Deng Xiaoping in ordering the military crackdown on Tiananmen Square on June 4, 1989, according to a copy of the manuscript seen by the South China Morning Post last night.

The original 279-page manuscript, entitled The Critical Moment and subtitled Li Peng Diaries, started to circulate in the run-up to the 21st anniversary of the crackdown.

In Hong Kong, Bao Pu - founder of the New Century Press that published Zhao's secret memoirs last year - said he was passed a copy of Li's diary by a 'middleman'.

Bao declined to say who the middleman was acting for. The book will be in traditional Chinese and renamed Li Peng's June 4 Diary.

It was not certain last night if the copy Bao had is exactly the same as the copy seen by the Post. But large sections are identical and each contains 34 photos purportedly picked by Li Peng for his unreleased book.

'The middleman approached me precisely because of my experience of publishing Zhao's memoirs,' said Bao, who is the son of Bao Tong - Zhao's top aide and the most senior official jailed over the 1989 democracy movement.

Bao said that after months of research, he and other editors agreed the book 'should be authentic' and 'it was very unlikely it was a fake'.

In a forward dated December 6, 2003, Li wrote: 'I feel responsible to write up what I know of the truth about this turmoil to serve as the most important historical testimony.'

Li's book was reportedly ready for publication in early 2004 to coincide with the 15th anniversary of June 4. Widely seen as the mastermind behind the military crackdown and held responsible for killing civilians, Li was eager to get his side of the story told. But the leadership under President Hu Jintao and Premier Wen Jiabao blocked publication.

Li, now 81 and reportedly in failing health, is believed to have worked hard on his memoirs since full retirement in 2003. His diaries on the construction of the Three Georges Dam and his economic management theories have already been published.

'From the beginning of the turmoil, I have prepared for the worst. I would rather sacrifice my own life and that of my family to prevent China from going through a tragedy like the Cultural Revolution,' Li wrote in the entry dated May 2, 1989. On April 27, he wrote that his car was blocked by student protesters on the way home but his driver and body guards turned around and drove off in the opposite direction.

Li detailed how the top leaders were divided about what to do about the protests, and noted that he began to have differences with Zhao as early as April 18, three days after the death of party secretary Hu Yaobang , which triggered the protests.

Li revealed how he and Zhao sparred during meetings of the Politburo and its Standing Committee. Li said he believed the movement was aimed at overthrowing Communist Party rule and thus insisted on labelling it 'counter-revolutionary'. Zhao advocated a soft approach, believing the students were patriotic.

Li indicates in clear terms that the big decisions, including sending troops to Beijing, were made by Deng. He said Deng made the decision to bring in the army to impose martial law at a meeting with five Politburo Standing Committee members and president Yang Shangkun at Deng's home on May 17.

All except Zhao supported Deng, though Hu Qili, Zhao's closest political ally in the Politburo, expressed his concern over the consequences, Li said in the diary entry that day. Coming out of Deng's home, Li said he was excited while Zhao was crestfallen.

In the entry for May 19, Li quoted Deng as saying that while the forces imposing martial law would try to minimise injuries, they should prepare to 'shed some blood'.

In the same entry, Li detailed how Jiang Zemin was selected to replace Zhao Ziyang that day. Before the start of a meeting, Deng told Li he would continue as premier and asked his opinion of Jiang as new party secretary. Li voiced his full support. Later in the meeting Deng told Li and several top leaders that Jiang would be new party chief.

Li wrote that Jiang was flown to Beijing on May 31 and told of his new job by Deng the next day. But Jiang repeatedly refused to take the job immediately, arguing that he wanted to become new party chief through an election specified by the party charter and asked Li to take charge until at least mid-June.

On the night of June 3, Li wrote that while he was in the Great Hall of the People holding meetings on sending troops into Tiananmen, Jiang was on the fourth floor of a nearby building monitoring activities in the square.