The company revealed to SEC that people with more than one Facebook profile account for 4.8% of the site’s monthly active users.

In a 10-Q filling with SEC, Facebook reported that out of its 955 million monthly active users approximately 83 million accounts are false.

"While these numbers are based on what we believe to be reasonable estimates of our user base for the applicable period of measurement, there are inherent challenges in measuring usage of our products across large online and mobile populations around the world," said Facebook.

In March 2012 Facebook reported that 5-6% of their accounts were duplicates or fake but the SEC filing reveals that the number is now 8.7%.

"If we fail to retain existing users or add new users, or if our users decrease their level of engagement with Facebook, our revenue, financial results, and business may be significantly harmed," said Facebook."

Security experts say Facebook’s report means users should beware on social media websites.

"The huge number of fake profiles on social media websites is very worrying and reinforces the need for users to be vigilant when sharing and surfing online," said Simon Ellson, internet security expert at Norton. "Remember that, unless your privacy settings are on high, social media networks and profiles are public arenas and can be viewed by anyone. With so many fakes out there, it’s important to think before you post."

Facebook shares continue to tumble after the release of its first earnings report which revealed the company had a net loss of $157m in its second quarter. Facebook shares have dropped to below $20 per share since going public in May at $38 per share.

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