Facebook’s oversight panel announced a probe into the company’s system for allegedly exempting high-profile users from its own rules on Thursday, accusing the embattled social media giant of a lack of transparency.

A series of damning Wall Street Journal stories based on whistleblower leaks has sparked outrage and renewed congressional scrutiny of Facebook’s impact on mental health as well as how it treats celebrities.

According to Journal reports citing internal documents, the so-called “cross-check” or “XCheck” system protects millions of elite users from rules that Facebook claims apply equally at the social media giant. In a blog post, the network’s semi-independent oversight board stated that it “has accepted a request from Facebook… to review the company’s cross-check system and make recommendations on how it can be changed.”

Facebook has faced a barrage of criticism in the last month after former employee Frances Haugen leaked internal studies revealing that the company was aware of potential harm stoked by its sites, prompting US lawmakers to renew their call for regulation.

The Facebook-funded oversight board, which is made up of experts who have the final say on what is removed or allowed to remain on the platform, also chastised the company for not being “fully forthcoming.”

“On some occasions, Facebook failed to provide relevant information to the Board, while on other occasions, the information it did provide was incomplete,” the panel said in response to questions about the cross-check system.

It specifically cited the platform’s ban on former US President Donald Trump, which it reviewed and ultimately upheld despite Facebook’s sometimes incomplete information.

Following that, Facebook increased Trump’s ban to two years, claiming that he deserved the maximum penalty for violating platform rules in connection with a deadly attack on the US Capitol by his supporters. When Trump’s two-year ban expires, Facebook will enlist experts to determine whether his activity on the social network still poses a threat to public safety.

“The credibility of the oversight board, our working relationship with Facebook, and our ability to render sound judgments on cases all rely on our ability to trust that information provided to us by Facebook is accurate, comprehensive, and paints a complete picture of the topic at hand,” the board wrote.

In a statement, Facebook pledged to be more specific in its responses to the panel’s questions. “We believe the board’s work has had an impact, which is why we asked the board for input into our cross-check system, and we will strive to be clearer in our explanations to them going forward,” according to the statement.

Facebook has reacted angrily to the criticism, claiming that journalists cherry-picked parts of its internal research to cast the company’s work in a negative light.

A double standard in content moderation would contradict Facebook’s assurances to the board.

The Journal cited examples of high-profile posts, including one from soccer star Neymar that showed nude images of a woman who accused him of rape and was later removed by Facebook. Because high-profile users’ posts drive engagement on the platform, keeping celebrities on Facebook is critical for a company interested in long-term growth.

The panel’s work, as well as the panel’s very existence, was criticized by an activist group calling itself The Real Facebook Oversight Board.

“The Oversight Board was always a Facebook PR stunt to cover up and deflect from the company’s own failure to keep hate, racism, and disinformation off its platforms,” the company said in a statement.