After several cases of apparent click fraud on Facebook were reported last month one company has decided to sue the social network over similar claims. Sports site RootZoo is accusing Facebook of charging for more clicks than it actually got and, backed by its internal measuring, will take the Palo Alto-based company to court in a lawsuit filed at the federal district court in San Jose, California.

RootZoo had been advertising with Facebook over several months, from November 2007 to June 2008, but allegedly found that its internal numbers didn't match those provided by the social network. The sports site presented the data for one day, June 2, 2008, when it claims that Facebook billed it for 804 clicks while it own internal logs showed only 300 clicks. After Facebook refused to provide the company with its logs or refund it for the false clicks RootZoo saw no other option than to file a lawsuit against the company.

A large number of similar click fraud claims surfaced last month, with advertisers claiming Facebook's numbers were off by 20 percent and sometimes even 100 percent. After the story broke the social network acknowledged the problem and said it was working on a solution though it provided no explanation for the issue. One theory generally put forward is that a new type of bots scraping Facebook data would have triggered the social network to register a click even though that never actually materialized in a visit for the advertisers.

"We have developed a series of sophisticated systems to detect suspicious clicks and ensure advertisers are not charged for this activity. In addition, we analyze tremendous amounts of data to discern larger click patterns and, in rare cases where this research or other analysis reveals advertisers have been charged for invalid clicks, we have always, and will continue to, issue credits to impacted advertisers," the Facebook responded, insisting that it was taking click quality very seriously and that this particular lawsuit was without base and unnecessary.