A collection of documents from Zhao Ziyang, who was China's reformist Communist Party chief until he was toppled in 1989 for opposing the Tiananmen crackdown, has been smuggled out of the country and will be published in Hong Kong this month, according to a publishing house that is turning them into a book.

"The Collected Works of Zhao Ziyang," to be released by the Chinese University of Hong Kong Press, lifts the veil on behind-the-scenes wrangling among top leaders from 1980 to 1989, said Gan Qi, director of the publisher. "The information in these documents provides concrete first-hand evidence of the existence of such conflicts," Gan said during an interview.

It is unclear if the documents still come under China's state secret laws. If they are classified it could provide a test of Beijing's commitment to academic and publication freedom in the former British colony, which reverted to Chinese rule in 1997. The territory was rocked recently by allegations that China had abducted and illegally detained five Hong Kong booksellers.