On a fourth-quarter earnings call Wednesday, Facebook chief executive Mark Zuckerberg lashed out at Apple, calling Apple anti-competitive at a moment when the social network itself is facing major federal scrutiny over antitrust issues.

“We increasingly see Apple as one of our biggest competitors,” Zuckerberg said, noting that Apple’s iMessage software is preinstalled on iPhones — enabling it to become the most widely used messaging service in the United States, as opposed to Facebook’s WhatsApp — and that Apple’s growing investment in services also enables it to compete with Facebook and other apps that use its iOS software platform.

“Apple has every incentive to use their dominant platform position to interfere with how our apps and other apps work, which they regularly do,” he said. “They say they are doing this to help people, but the moves clearly track their competitive interests.”

Zuckerberg’s comments, at a moment when the social network is being accused of major antitrust violations by the Justice Department, seemed intended to paint Facebook as not a monopoly but a service that faces significant competitive threats, and to point out that its rival tech giant is even more powerful than Facebook. Apple is the world’s wealthiest company by market capitalization; Facebook is the sixth.

Zuckerberg also accused Apple of providing false assurances on user privacy. He said that while Apple claims its iMessage software is encrypted and protects privacy, the company stores a backup of people’s messages. He contrasted that with the practices of WhatsApp, which does not.

He also reiterated messaging from Facebook that upcoming changes to Apple’s iPhone software would disproportionately harm Facebook and small businesses that rely on personalized advertisements to reach customers and find new ones. Apple says that it made its policy change to limit data collection in order to protect user privacy.