A leading Australian publisher claims the threat of Chinese Government retaliation is the reason it cancelled plans to print a book which further exposes Beijing's influence on Federal Parliament and other parts of society.

Key points: Publisher concerned about "potential threats" and "possible action" by Beijing

Publisher concerned about "potential threats" and "possible action" by Beijing Book closely examines the Chinese Communist Party's activities in Australia

Book closely examines the Chinese Communist Party's activities in Australia Cancellation comes amid heightened debate over growing influence of China

Prominent Charles Sturt University academic Clive Hamilton said Allen & Unwin was ready to publish his manuscript Silent Invasion, but last week informed him it could no longer proceed because it was worried about defamation action.

"Allen & Unwin said that they were worried about retaliation from Beijing through a number of possible avenues including legal threats, orchestrated by Beijing, and they decided it was too big a risk and so therefore pulled the plug and returned the rights to me," Professor Hamilton said.

Silent Invasion closely examines the Chinese Communist Party's activities in Australia, and Professor Hamilton said it had already been significantly edited by lawyers.

"We have no doubt that Silent Invasion is an extremely significant book," the company wrote to the author in a confidential email to the author on November 8, which has been seen by the ABC.

The publisher said it was concerned about "potential threats to the book and the company from possible action by Beijing".

In the email the company explained: "The most serious of these threats was the very high chance of a vexatious defamation action against Allen & Unwin, and possibly against you personally as well."

Allen & Unwin was "an obvious target" for "Beijing's agents of influence", the publisher added.

'Autocratic foreign power' influencing Australian publisher: Hamilton

Professor Hamilton, who has published eight previous books with Allen & Unwin and has received an Order of Australia for his contribution to public debate, said the publisher's change of heart is a "watershed in the debate over China's suppression of free speech".

"What we're seeing … is the first instance where a major Western publisher has decided to censor material of the Chinese Communist Party in its home country," he said.

"The book is of enormous public interest, it will sell very well I expect, and we as Australians living in a free society should not allow ourselves to be bullied into silence by an autocratic foreign power."

In a statement, Allen & Unwin said it had "enormous respect" for Professor Hamilton and his work but after extensive legal advice decided to delay publication "until certain matters currently before the courts have been decided".

"Clive was unwilling to delay publication and requested the return of his rights, as he is entitled to do. We continue to wish him the best of luck with the book," the publisher said.

The cancellation of the publication comes amid heightened debate in Australia over the growing influence of China, including warnings from politicians and public officials about the need to protect freedom of speech.

The Turnbull government is expected to soon unveil new legislation to counter foreign interference in Australia's democracy, a fact Allen & Unwin also acknowledged in its email to Professor Hamilton.

"We … understand that our position would be stronger once proposed legislation targeting foreign influence in Australia passes through parliament, and it sounds as though this is now unlikely to happen until next year," the company wrote.