By Alex Heath

The ongoing feud between Apple and Facebook just heated up.

Apple ($AAPL) said on Wednesday that it revoked Facebook’s ($FB) access to its Developer Enterprise Program, a move that kneecaps the social network and marks a steep escalation of tensions between the two tech giants.

On Tuesday, TechCrunch’s Josh Constine reported that Facebook has been paying people $20 per month to install unofficial apps that log all of a phone’s activity, including web traffic. Facebook had been quietly running the program for years, but quickly shuttered it on Apple devices following public backlash over the TechCrunch report.

The surfacing of Facebook’s covert program, which was used to conduct competitive and behavioral research, instantly put the embattled company at further odds with Apple. The iPhone maker's CEO, Tim Cook, has been publicly preaching the need for sweeping data privacy regulations in the U.S., while at the same time criticizing the data-hungry business model that Facebook practices.

This time, Apple’s retaliation wasn’t a matter of ideological differences, but rather a response to Facebook’s violation of Apple’s policy.

According to TechCrunch, Facebook bypassed the App Store with its research apps by using something called Apple’s Enterprise Developer Program.

The program essentially gives employees within a company the ability to install applications on Apple devices without making them publicly available in the App Store — a process that would require vetting by Apple. Apps in the App Store are subject to more stringent rules about the content they can include and the data they can collect.

Facebook’s sidestepping of the App Store and its use of the enterprise program to distribute apps to non-employees means that Facebook violated its developer agreement with Apple, the company confirmed in a statement to Cheddar:

“We designed our Enterprise Developer Program solely for the internal distribution of apps within an organization. Facebook has been using their membership to distribute a data-collecting app to consumers, which is a clear breach of their agreement with Apple. Any developer using their enterprise certificates to distribute apps to consumers will have their certificates revoked, which is what we did in this case to protect our users and their data.”

This doesn’t mean that Facebook is being removed from the App Store. But it does mean that Facebook will no longer be able to widely distribute apps on Apple’s platform without approval.

It also means that, or now, Facebook employees can't use unreleased apps on Apple devices. Facebook is famous in Silicon Valley for "dog fooding," a practice in which employees internally test new features before they are released to the public. Employees use internal apps for everything from testing bugs in software to coordinating the use of private shuttle buses that take them to and from work every day.

Because of Apple's sudden action against Facebook, people familiar with the matter told Cheddar that Facebook employees are unable to use their internal apps on Apple devices. Some Facebook employees privately voiced concern on Wednesday that Facebook is being unfairly targeted by Apple, the people said.

Facebook did not immediately respond to a request for comment about Apple’s revoking of its Enterprise Developer Program license. Facebook said earlier that it would continue the same research program on Google’s Android, which has more lenient app rules than Apple.