Facebook is less popular than anyone thought. The world’s leading social network site has revealed that its previous estimate of 845 million users was inaccurate because it included millions of “fake users” whose accounts are either for false personalities or duplicates of other accounts.

A securities filing by the company revealed that Facebook estimates that between 5 to 6 per cent of its accounts fall into this category, which translates to between 42 million and 51 million accounts.

In the same filing, Facebook also revealed that it had opened new lines of credit worth 8 billion dollars. The company said it would use the funds to pay general corporate expenses, as well as to finance the tax liabilities of employees, who exercise their stock options, and to cover the potential legal costs of patent litigation with Yahoo, which has accused Facebook of violating 13 of its patents.

Facebook filed earlier this year its intention to launch an IPO (initial public offering), in which it hopes to raise 5 billion dollars at a reported company valuation between 75 billion dollars and 100 billion dollars.