Lawmakers say they want to hear from Facebook’s CEO Mark Zuckerberg after an alleged major data mining operation affecting users was revealed.

The calls come after reports that Cambridge Analytica, a British consulting firm that worked for the 2016 Trump campaign, allegedly harvested data from millions of Facebook users without their knowledge or permission.

Cambridge Analytica denies using the information, but Mark Warner, the top Democrat on the Senate Intelligence Committee, wants to hear from Zuckerberg.

"He needs to come out, he created this entity, created this industry and he needs to come explain to the American public and to policy makers," said Warner.

On Friday, the House Committee on Energy and Commerce said it would hold a hearing on the incident, and called for Zuckerberg to testify before Congress. Zuckerberg previously told CNN he is open to it.

Facebook took out full-page ads in several major publications in the United States and the United Kingdom on Sunday apologizing for a "breach of trust."

Not all users have been forgiving, as #DeleteFacebook" trended on Twitter.