A row has blown up between Facebook and academics over the use of its data for reporting trends on the social network.
Members of the Cybersecurity for Democracy team, based at New York University, tweeted they had had their accounts shut down.
Facebook said the tools they had used to gain access to its data violated user privacy.
The researchers said Facebook was now curtailing their work measuring vaccine disinformation, among other things.
'Healthy internet'
Laura Edelson tweeted Facebook had suspended the accounts of several people associated with the team, including her own.
"The work our team does to make data about disinformation on Facebook transparent is vital to a healthy internet and a healthy democracy," she added.
Other academics replied expressing concern, with one saying the same thing had happened to them.
The BBC is not responsible for the content of external sites.
View original tweet on Twitter
But Facebook product management director Mike Clark blogged research should not happen at the expense of people's privacy.
"The researchers gathered data by creating a browser extension that was programmed to evade our detection systems and scrape data such as usernames, ads, links to user profiles… some of which is not publicly viewable on the platform," he said.
"The extension also collected data about Facebook users who did not install it or consent to the collection."
The company offered researchers a number of "privacy-protective methods" to collect and analyse data, Mr Clark said.
"We welcome research that holds us accountable and doesn't compromise the security of our platform or the privacy of the people who use it, " he added.
'No choice'
Last summer, the researchers were told their Ad Observatory browser extension violated Facebook's terms and asked to stop scraping data from the platform.
And Facebook told BBC News it had been left with "no choice but to disable the researchers' developer access, accounts and apps" after repeatedly explaining its concerns.
The decision to shut down their access comes against a backdrop of Facebook overhauling the way researchers use its tools.
A new-look application programming interface (API) designed specifically for access by researchers is coming later this year.
Right-wing news
Facebook eliminated many ways to access data in the wake of the Cambridge Analytica scandal.
And the new research API is pitched as a way to open some of that material up once more.
Meanwhile, Crowdtangle, a Facebook-owned data tool that allows researchers, fact-checkers and journalists to follow, analyse and report on trends across social media, is being integrated into its wider transparency tools.
But New York Times journalist Kevin Roose, who used Crowdtangle to report right-wing news was seeing far more engagement among Facebook users than mainstream stories, suggested its decision to downgrade the service was part of a wider public-relations plan for Facebook to "manage its reputation".