Facebook shut down accounts belonging to two academic researchers late Tuesday, cutting off their ability to study political ads and misinformation on the world’s biggest social network.

The company accused the academics of engaging in “unauthorized scraping” and compromising user privacy on the platform, claims that Facebook’s many critics are slamming as a thin pretense for killing the transparency work.

The company took action against Laura Edelson and Damon McCoy, two well-known researchers affiliated with NYU’s Cybersecurity for Democracy project who have long sparred with the company. The move cuts off their access to Facebook’s Ad Library — one of the company’s only meaningful transparency efforts to date — and data on popular posts from the social media monitoring service Crowdtangle.

Facebook has a history with Edelson and McCoy. The company served the pair cease and desist letters just weeks before the 2020 election, calling on the team to disable an opt-in browser tool called Ad Observer and unpublish their findings. Ad Observer is a browser tool anyone can install that’s designed to give researchers a rare glimpse into how Facebook targets the ads that have transformed it into a trillion-dollar company.

“Over the last several years, we’ve used this access to uncover systemic flaws in the Facebook Ad Library, identify misinformation in political ads including many sowing distrust in our election system, and to study Facebook’s apparent amplification of partisan misinformation,” Edelson said on Twitter.

“By suspending our accounts, Facebook has effectively ended all this work. Facebook has also effectively cut off access to more than two dozen other researchers and journalists who get access to Facebook data through our project, including our work measuring vaccine misinformation with the Virality Project and many other partners who rely on our data.”

The incident set off a fresh round of criticism about the company’s preference for opacity over transparency when it comes to some of the more dangerous behavior that the platform incubates.

By Wednesday, Facebook’s actions had attracted the attention of some members of Congress. Sen. Ron Wyden (D-OR) criticized Facebook’s decision to punish the researchers under the pretense of protecting users in light of the company’s long history of invasive privacy practices. Wyden also called Facebook’s bluff over its claim that revoking researcher access is an effort to comply with a privacy order from the FTC that the company was issued for its previous user privacy violations.

Sen. Mark Warner (D-VA) also weighed in on Facebook’s latest controversy, calling the decision “deeply concerning.” Warner praised independent researchers for “consistently [improving] the integrity and safety of social media platforms by exposing harmful and exploitative activity.”

“It’s past time for Congress to act to bring greater transparency to the shadowy world of online advertising, which continues to be a major vector for fraud and misconduct,” Warner said.

A number of free press organizations, researchers and misinformation experts also condemned Facebook’s decision Wednesday. “Facebook’s cavalier approach to privacy enabled it to become so dominant,” The Markup’s Julia Angwin and Nabiha Syed wrote in a joint statement.

“But now, when independent researchers want to interrogate that platform and the influence it commands, Facebook is propping up user privacy as a shield to hide behind.”