More than 20 years after Chinese troops crushed pro-democracy protests, a top Tiananmen Square student leader says the bloodshed was unavoidable as the communist leadership was set on using force.

In a new book, Chai Ling, the students' commander-in-chief who later escaped China in a cargo box, recounts years of anguish as she wrestled with memories of Tiananmen and describes how more recently she found a calling in faith.

Chai, who is now 45 and lives in Boston with her American husband and three daughters, voices outrage at Tiananmen accounts that charge that she could have ordered students out more quickly or that she sought a violent showdown.

"The bottom line for me about Tiananmen Square is that the student leaders never expected, hoped for or anticipated the Chinese government would actually open fire on its own citizens," she writes in "A Heart for Freedom," which will be released in October in English and Chinese.

Chai dismisses suggestions that an earlier exit from Tiananmen Square would have saved the lives of the hundreds if not thousands who were killed, believing that hardliners in the communist leadership would have found another pretext to rein in expanding protests.

"The government was determined to retake control of the city and send a message of fear and intimidation to the people -- to 'kill the chicken to shock the monkey,' as the Chinese saying goes," she writes.

Chai says she believes the leadership decided to use force as far back as April 25, 1989, when supremo Deng Xiaoping accused students of seeking to topple the Communist Party. A state media editorial the next day warned that the leadership would end the "turmoil."

After a month in which protests grew and perceived moderate Zhao Ziyang was put under house arrest, tanks rolled through Beijing on June 3. In the early hours of June 4, students who remained in Tiananmen Square voted on whether to stay or leave.

In Chai's account, the voice vote's result was indecipherable and soldiers opened fire at the same time, leading to chaos. Fellow leader Feng Congde, then Chai's husband, determined that students voted to leave but not all protesters heard, Chai writes.

"When we were on the Square, we didn't have all the information necessary to make strategic decisions," she writes.

Controversy over Chai's role stems largely from a taped interview she gave to American Philip Cunningham, then a student, shortly before the crackdown. In a later documentary, Chai is heard saying that "what we are actually hoping for is bloodshed."

Chai insists in the book that her words were taken out of context. Chai has spoken before about Tiananmen but says that she wanted to give her version at greater length.

More important to her, Chai said that she wanted to relate her embrace of faith in 2009. Chai -- who prefers to call herself a Jesus-follower, saying the term is more inclusive than Christian -- brought a Bible to an interview with AFP and spoke at length about Jesus Christ.

"All my life I was made to try to save China. I couldn't do it. But if you can, I give my life to you," she said of Christ.

"Little did I know, I felt like I do end up with a much better bargain. My life was saved, and he'll continue saving China," she said.

In her book, Chai for the first time writes at length about how she underwent several abortions. Chai has launched a group called All Girls Allowed which aims to end forced abortions against girls in China, where the government restricts most women from bearing more than one child.

Describing her first abortion when she was a university student, she writes that her father sent her on a bus to a hospital where no one would recognize her. Chai writes that "pain and shame engulfed me" after the operation.

Chai drew a parallel between abortion and Tiananmen Square and said that she saw both herself and Deng Xiaoping as sinners.

"But still, today we have hope and confidence that this vicious cycle of massive killing and violence can come to an end because of God's grace and his power to save," she said.