Facebook's latest figures showing growth in global users also suggest as many as 83 million may come from dubious sources -- duplicate accounts, pages for pets and those designed to send spam.
Facebook members grew to 955 million at the end of the second quarter, but some 8.7 percent may be dodgy, the company said in its quarterly filing with the US Securities and Exchange Commission.
There are "inherent challenges" in measuring usage "despite our efforts to detect and suppress such behavior," the social network said.