Google has been ordered to reveal the identity of an anonymous online reviewer known only as CBsm 23 to allow a Melbourne dentist to bring defamation action against the individual.

In a landmark ruling this week, the Federal Court declared that the web giant must hand over information that would help dental surgeon Mathew Kabbabe track down the mystery reviewer.

Kabbabe intends to bring a defamation action against the individual, who is alleged to have damaged his teeth whitening business by posting a negative review under the pseudonym CBsm 23.

CBsm 23 posted a review warning other patients to “STAY AWAY” from the business, claiming the experience there was “extremely awkward and uncomfortable”.

The user suggested the whitening procedure performed by the dentist “was not done properly”, a “complete waste of time” and that it seemed like the dentist “had never done this before”.

After trying - and failing - to get Google to take down the negative review, Kabbabe appealed for information about the identity of the user to be released, which the web giant declined.

“[We] do not have any means to investigate where and when the ID was created,” Google wrote to him in an email earlier this year.

On Wednesday, Justice Bernard Murphy deemed “it appropriate to accede to the application and to grant leave to Dr Kabbabe to serve the proceeding on Google in the USA”.

Under the order, Google will be required to provide subscriber information associated with CBsm 23’s account, including any names, phone numbers, IP addresses and location metadata.

“I consider that Google is likely to have or have had control of a document or thing that would help ascertain that description of the prospective respondent CBsm 23,” Justice Bernard Murphy said.

The order also applies to “any other Google accounts ... which may have originated from the same IP address during a similar time period to when CBsm 23’s account was accessed to post the offending Google review”.