Facebook fired back against a group of academics from Belgium who derided the social network's tracking methods, data sharing and ambiguity in its advertising systems.

Except for a bug that tracked all users who visited certain Facebook pages, Facebook doesn't practice tracking nonusers, the company said in response to the criticism.

The scathing report, commissioned by the Belgian Privacy Commission (BPC), is titled "From social media service to advertising network: A critical analysis of Facebook's Revised Policies and Terms."

The document rips apart Facebook's revised policies. Many of these policies, the authors stated, haven't improved. One of the allegations that stands out in the report is the assertion that Facebook tracks nonusers as well as users.

"Facebook places cookies whenever someone visits a webpage belonging to the facebook.com domain, even if the visitor is not a Facebook user," states the report. "For nonusers, one of the cookies placed by Facebook (called 'datr') contains a unique identifier and has an expiration date of two years."

Richard Allan, Facebook's vice president of policy for Europe, responded to the above allegation and also the issue on social plugins. Facebook allegedly uses social plugins to spread cookies to the browsers of nonusers, the report states.

"This is not our practice," states Allan. "However, the researchers did find a bug that may have sent cookies to some people when they weren't on Facebook. This was not our intention - a fix for this is already underway."

While Allan countered several allegations raised by the BPC's report, he didn't address all of the issues that were raised.

The report alleges that Facebook doesn't give users the ability to stop the transmission of their data to the social networking company and third parties.

"In other words: users are able to choose from several granular settings, which regulate access by other individuals, but cannot exercise meaningful control over the use of their personal information by Facebook or third parties - this gives users a false sense of control," states the report.

In addressing a slightly different point, Allan pointed out that Facebook makes it known that the company "may" share user information with third parties.

"When we updated our Data Policy in 2015, we were clear that it did not change the commitments our companies have made; their terms and privacy policies continue to be in effect," says Allan. "In the policy, we note that information may be shared among those companies."