The Senate Committee on Commerce, Science, and Transportation on Friday asked Facebook CEO Mark Zuckerberg to testify.

Two congressional committees have now asked Zuckerberg to appear, while others are said to be preparing to do so.

The Senate Committee on Commerce, Science, and Transportation on Friday requested public testimony from Mark Zuckerberg, the Facebook founder and CEO, adding to the list of congressional panels looking to haul in the company's top executives.

"During our time leading the Commerce Committee, several questions about Facebook's responsibilities and obligations to users have arisen even as the company's reach and importance have grown," Republican Sen. John Thune and Democratic Sen. Bill Nelson said in a statement on behalf of the committee. "As a result, we have decided to ask Facebook CEO Mark Zuckerberg to testify before our committee.

"On a bipartisan basis, we believe Mr. Zuckerberg's testimony is necessary to gain a better understanding of how the company plans to restore lost trust, safeguard users' data, and end a troubling series of belated responses to serious problems," the two senators added. "We appreciate the efforts Facebook and its employees have already made to assist our committee and will work with them to find a suitable date for Mr. Zuckerberg to testify in the coming weeks."

Thune and Nelson also noted that Facebook had not responded to a series of questions from the committee about the recent privacy scandal involving the data firm Cambridge Analytica. The responses are due next Thursday.

Facebook officials briefed staffers on various congressional committees on Thursday, but Business Insider has reported that many of the committees were unsatisfied with the answers they did receive, increasing the likelihood of marathon hearings for Zuckerberg soon.

The House Committee on Energy and Commerce has also requested Zuckerberg's testimony, while the Senate Judiciary Committee has been mulling doing so since two senators asked its chairman, Sen. Chuck Grassley, to bring the billionaire in for a public hearing.

And simple requests for Zuckerberg's testimony may be the tip of the iceberg. Some lawmakers have expressed a desire to subpoena Zuckerberg and Facebook for testimony and any relevant documents for an investigation.