Russian hackers are selling private messages from 81,000 Facebook accounts online, an investigation has found.

The messages were posted on a forum by hackers claiming to have access to the personal data of 120 million accounts, offering to sell them at 8p per profile, according to the BBC.

Facebook has denied hackers gained access to its servers and instead blamed the breach on users who have installed malicious web browser extensions that can store private messages.

“We sell personal information of Facebook users. Our database includes 120 million accounts," one advert said. However, BBC News was only able to verify that data from 81,000 accounts had been stolen.

Cybersecurity expert Joseph Carson, chief security scientist at Thycotic, said that hackers are likely to have exaggerated the amount of data they have available.

“It is very unlikely that the cybercriminals have all the private message for 120 million accounts,” he said. “It is however, more likely that the published list of 81,000 accounts is all that the cybercriminals have, and they are looking to cause disruption and fear.”

The platform where the data was posted appears, or has been made to appear, to have Russian links. It is attached to a St. Petersburg based IP address.