The gathering came as part of Zuckerberg’s rare swing through Washington. His meetings with top lawmakers on Capitol Hill are putting him face-to-face with some of the tech giant’s foremost critics as it is under state and federal investigation over potential antitrust violations.

Warner said one member, whom he declined to identify, specifically raised questions about Libra, a cryptocurrency that regulators around the world have panned in recent months. Facebook announced Libra and Calibra, a subsidiary that shares the name of Facebook’s virtual wallet service, earlier this year. Facebook has said that it plans to make the cryptocurrency available to its roughly 2 billion users worldwide and that it will be run through an association based in Switzerland.

“One of the things I’m very worried about is, when the Facebook representative testified before the Senate, before my committee, he said, ‘You know, if we can’t get American regulatory approval, we won’t launch,’ ” Warner said. “We hear lots of indication Facebook may choose to launch in other nations first. … So somebody is not telling the truth.”

Warner declined to say more about Facebook’s response, but he added: “He heard the concerns, but I still don’t have 100 percent clarity on whether they feel like they can launch short of U.S. regulatory approval.”

Facebook did not immediately respond to a request for comment.

Among the lawmakers Zuckerberg is slated to meet with this week are, according to their offices, Sen. Richard Blumenthal (D-Conn.), who has sharply criticized Facebook’s privacy practices; Sen. Mike Lee (R-Utah), the leader of a key antitrust subcommittee; and Rep. Adam B. Schiff (D-Calif.), who has investigated Silicon Valley’s efforts to defend U.S. elections from foreign interference.

“We talked about some of the most pressing challenges facing the tech industry, including its repeated failures to [protect] election security and consumer privacy,” Blumenthal, who joined the dinner, said in a statement. “I focused on the challenges of privacy safeguards and I welcome the strong, constructive interest shown by Mr. Zuckerberg.”

Zuckerberg’s visit to the Capitol marks his first known trip here since he testified for roughly 10 hours in front of lawmakers furious with Facebook over its privacy scandals. On Wednesday, the tech giant said the purpose of the visit is to discuss the “future of Internet regulation,” months after Zuckerberg called on regulators to take a “more active role” on issues related to Internet policy, including areas such as online extremism, political advertising and data privacy.

“The rules governing the Internet allowed a generation of entrepreneurs to build services that changed the world and created a lot of value in people’s lives,” he wrote in an op-ed for The Washington Post in March. “It’s time to update these rules to define clear responsibilities for people, companies and governments going forward.”

With Libra, Zuckerberg may face an onslaught of opposition. The Trump administration has expressed early concerns that Facebook has not fully grappled with the threats of money laundering and other risks associated with Libra. Federal Reserve Chair Jerome H. Powell has said the cryptocurrency poses “serious concerns.” Even President Trump has weighed in, tweeting that Libra lacked “dependability” before suggesting it should be subject to banking regulations.

The criticisms set the stage for two tense congressional hearings in July with David Marcus, who oversees Facebook’s work on blockchain, the technology underpinning cryptocurrency. Sen. Sherrod Brown (D-Ohio), the top Democrat on the Senate Banking Committee, blasted Facebook as “dangerous,” adding that it would be “crazy to give them a chance to experiment with people’s bank accounts,” given the company’s previous missteps.