Before it descended into frustration, the meeting had been billed as part of Mr. Zuckerberg’s apology tour for Facebook’s mishandling of its users’ data.
European authorities have emerged as the world’s most assertive watchdog of the technology industry, and many wanted a chance to publicly grill the chief executive after revelations in March that a British political consulting firm, Cambridge Analytica, had improperly obtained and used the information of millions of Facebook members.
But the session with Mr. Zuckerberg, which was scheduled for one hour and 15 minutes, was set up so that lawmakers asked questions one after the other without a pause for answers.
That left Mr. Zuckerberg only minutes to speak at the very end, allowing him to select which questions to address in a general way.
“Mark Zuckerberg is getting away without responding to citizens concerns,” Udo Bullmann, the leader of the Socialists and Democrats roup in the European Parliament, tweeted later. “We need a real back and forth with all the relevant MEPs in the room.”
Mr. Zuckerberg’s visit to the European Union’s typically sleepy Parliament starkly contrasted with his grilling in Congress last month over the Cambridge Analytica revelations.
Over two days of appearances on Capitol Hill, which were televised live and became a media spectacle, Mr. Zuckerberg faced hours of questions from lawmakers and repeatedly said Facebook could do better.
Mr. Zuckerberg had initially resisted meeting with the European authorities, and his appearance on Tuesday was a limited concession.
Europe’s Parliament is markedly weaker than Congress, and it does not have the power to regulate Facebook. The session was originally scheduled to be held behind closed doors, but after an outcry in Brussels, Facebook agreed to make the questioning public by streaming it online.
Mr. Zuckerberg’s spoke ahead of the European Union’s introduction of a strict data privacy law, the General Data Protection Regulation, on Friday. The rules, among the toughest in the world, empower regulators to fine companies up to 4 percent of their global revenue for privacy violations — equivalent to $1.6 billion for Facebook.
The meeting with Mr. Zuckerberg brought a rare buzz to the European Parliament. The body’s live stream for his appearance temporarily crashed, most likely because of the high interest in the meeting. Security around the Parliament building was extremely tight, at a level typically reserved for national leaders.
“People are thrilled to put Zuckerberg on the grill,” said Karl Pincherelle, an aide to a French member of the European Parliament.
Mr. Zuckerberg began the meeting by keeping to the conciliatory script he had used in Washington. He read a statement in which he apologized for Facebook’s role in the spreading of misinformation, foreign interference in elections and the mishandling of customer data. Then the questions began.
“It is time to discuss breaking Facebook’s monopoly,” said Manfred Weber, a German lawmaker and the leader of the European People’s Party, which makes up the biggest bloc in Parliament. He added that the company had “too much power.”
Another member asked if Mr. Zuckerberg wanted to be remembered in the same high regard as Steve Jobs and Bill Gates, or for undermining democracy. In all, nearly a dozen lawmakers spoke, each with multiple questions, some of them very detailed and pointed about issues such as online bullying and election interference.
Throughout, Mr. Zuckerberg, dressed in a dark suit and purple tie, sat stone-faced, jotting down notes and occasionally sipping from a glass of water.
Once the lawmakers finished asking their questions, Mr. Zuckerberg largely avoided answering specifics and repeated previous statements.
He mentioned Facebook’s development of artificial intelligence technology to spot violent content and bullying, and its partnerships with fact-checker groups to prevent the spread of misinformation. He also referred to setting up Facebook in his Harvard dorm room, something he frequently noted during his testimony to Congress.
The largely rote responses drew the ire of lawmakers as Mr. Zuckerberg concluded, saying he wanted to be “sensitive to time” after the meeting went 15 minutes past its agreed-to length.
It was left to Antonio Tajani — the president of the European Parliament, who had proudly announced on Twitter just days earlier that Facebook’s chief would attend a session in Brussels — to respond to lawmakers’ criticism.
In the end, Mr. Zuckerberg agreed to respond to their questions in writing. Mr. Tajani later said that he had devised the format of the questioning because the European Parliament typically does not invite chief executives for meetings and so was treating him as a private citizen. Ultimately, it all lasted less than two hours. As lawmakers headed for a news conference, Mr. Zuckerberg made a swift exit.
He was next set to visit Paris, with a lunch scheduled on Wednesday with President Emmanuel Macron. Asked about the time constraints by his frustrated fellow members of Parliament, Mr. Tajani referred to the Facebook executive’s travel schedule saying,
“There is a flight.” He insisted at a news conference afterward that the meeting had been “a great success.”
Others said more needed to be done. Guy Verhofstadt, president of the Alliance of Liberals and Democrats for Europe group, tweeted:
“Today’s pre-cooked format was inappropriate & ensured Zuckerberg could avoid our questions. I trust that written answers from Facebook will be forthcoming. If these are not accurately answered in detail, the EU competition authorities must be activated & legislation sharpened.”