Facebook is challenging the report we reported on yesterday that said user numbers were dropping in the US, UK, and other countries that have had the service for a while.

Here’s what a Facebook spokesperson told Marketplace yesterday:

“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. 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 on any given day.”

From the BBC:

(Facebook) told the BBC it had seen a 21% growth for US users on Facebook during May, while the UK gained 368,000 new recruits between February and May.
According to comScore, the average amount of time spent on the site was also up, from 21 minutes per day in December 2009 to 25 minutes per day by December 2010.
Measurement firm Nielsen said its figures also showed growth.
“There are months when figures dip but I’d be very cautious on calling a trend based on two months,” said Nielsen spokesman Neil Beston.