Facebook said this week it believes it has more than 83 million illegitimate accounts on its social media network.

Registered users with duplicate profiles made up 4.8 percent of membership figures, according to company filings published this week. In total, nearly 9 percent of its 955 million active accounts broke rules.

Facebook defined duplicates as “an account that a user maintains in addition to his or her principal account,” BBC reported.

It said profiles were “user-misclassified” if “users have created personal profiles for a business, organization, or non-human entity such as a pet.”

The network, whose business model relies on targeted advertising, has seen increased questioning over the worth of its advertising model which promotes the gathering of “likes” from users, BBC said.

"We generate a substantial majority of our revenue from advertising," the company said in its filing. "The loss of advertisers, or reduction in spending by advertisers with Facebook, could seriously harm our business."