Facebook, which does not usually comment on third party statistics, questioned the report saying that the data extracted for the report was not a relevant source for tracking the overall growth of Facebook.
"From time to time, we see stories about Facebook losing users in some regions. Some of these reports use data extracted from our advertising tool, which provides broad estimates on the reach of Facebook ads and isn't designed to be a source for tracking the overall growth of Facebook," the firm, with more than 650 million active users, said in a statement.
"We are very pleased with our growth and with the way people are engaged with Facebook. More than 50% of our active users log on to Facebook in any given day," it added.
The data gathered from Facebook's advertising tool by the site Inside Facebook found that Facebook's growth rate went down from 20 million new users in Apr 2010 to mere 13.9 million new users in April 2011 and to 11.8 million in May.
Rubbishing these reports, Facebook said BBC it had seen a 21 percent growth for US users during May, while the UK gained 368,000 new recruits between Feb and May.