The company introduced the service in May last year, after Chinese web users complained of inconsistent results, connection issues and error messages after using certain characters in search phrases.

Last Friday, Chinese censorship blog GreatFire.org reported that the Google had turned off the feature "sometime between 5 December and 8 December".

Google later confirmed the fact that it had removed the feature in December.

"Since Google moved its search engine to Hong Kong in 2010, censorship of its services such as YouTube, Google+ and thousands of keywords on Google Search has been done by the Great Firewall, out of control of Google," GreatFire.org wrote in the blog post. "The latest decision is entirely determined by Google and can only be described as self-censorship.

"This means that Google as an anti-censorship fighter may be unworthy of the name."