Chen Xitong, who was Beijing mayor during the 1989 crackdown on Tiananmen Square pro-democracy protests, said he was "sorry" and that the deaths could have been avoided, according to a book to be released this week.

Chen, who fell from grace in one of China's biggest political scandals, was widely seen as the official who pushed for the use of military force against the student-led protests in the heart of the capital.

The 81-year-old, who in 1998 was sentenced to 16 years in jail on corruption charges, however attempted to play down his role in the new book, saying he was merely acting on orders from the top leadership.

"I feel sorry," Chen said in the Chinese-language book "Conversations with Chen Xitong" which will hit Hong Kong book stores on Friday ahead of the 23rd anniversary of the Tiananmen Square crackdown.

"Nobody should have died in the June 4 incident if it was handled properly. I feel sorry, but I could not do anything, very sorry," he said, according to a copy of the book given to AFP.

"I believe the truth of the 1989 episode will be uncovered one day," Chen told Chinese scholar and author Yao Jianfu, who wrote the book based on eight interviews with Chen between January 2011 and April this year.

Chen was said to be one of the hardliners who lobbied for the use of military force and misled then leader Deng Xiaoping by exaggerating the protests in a bid to get Deng to authorise the use of the army to crush them.

He was promoted to Communist Party secretary of Beijing and made a member on the all-powerful Politburo, China's de facto ruling body, after the crackdown -- widely seen as a reward for his role in the Tiananmen episode.

He was however dismissed from his posts in 1995 and convicted later on corruption charges, becoming the first Politburo member to be jailed since the end of the Cultural Revolution in 1976. Chen won medical parole in 2004.

Chen described his downfall as "the biggest case of injustice since the Cultural Revolution".

But he denied trying to undermine then president Jiang Zemin, rejecting claims that his fall from grace was linked to his attempts to weaken the leader. "I have never opposed Jiang Zemin," he said.

Chen's downfall was one of the biggest political scandals in China in living memory, but has been eclipsed by the sacking of Chongqing party boss Bo Xilai in March, in a case that has exposed deep divisions among China's leaders.

Publisher Bao Pu of Hong Kong's New Century Press said the book was a "rare first-person account regarding the Tiananmen crackdown from a man widely believed to be responsible for the government's violent solution".

The publisher has no plans to launch the book on mainland China, where the Tiananmen protests remain a taboo topic.

Hundreds, perhaps thousands, are believed to have died when the government sent in tanks and soldiers to clear Tiananmen Square on the night of June 3-4, 1989, bringing a violent end to six weeks of pro-democracy protests.

An official verdict after the protests called them a "counter-revolutionary rebellion" although the wording has since been softened.