Google executive chairman Eric Schmidt claims that China is "the most sophisticated and prolific" hacker of foreign companies, according to reports.

Schmidt made the remarks about China in his soon-to-be-released book, "The New Digital Age," which was obtained by the Wall Street Journal (WSJ).

The book, which is scheduled to be released in April this year, was written by Schmidt and Google Ideas director Jared Cohen.

WSJ quoted the authors in the book as saying that "The disparity between American and Chinese firms and their tactics will put both the government and the companies of the United States at a distinct disadvantage."

"The United States will not take the same path of digital corporate espionage, as its laws are much stricter (and better enforced) and because illicit competition violates the American sense of fair play."

"This is a difference in values as much as a legal one."

According to WSJ, the book acknowledges that the US is far from an angel and from high-profile cases of cyber-espionage such as the Stuxnet virus that targeted Iranian nuclear facilities, to exports of surveillance software and technology to states with bad human rights records, there is plenty at home to criticise.

In July 2011, the US government cyber security experts warned that the adapted versions of the Stuxnet virus could cripple power, water and other vital services of the West.