Facebook CEO Mark Zuckerberg apologized to leaders of the European Parliament Tuesday for not doing enough to protect user data.
A new European data-protection law goes into effect Friday.
Follow along with Mark Zuckerberg testimony updates below
Zuckerberg: Facebook to be "fully compliant" with new data laws
2:20 p.m. ET: Mark Zuckerberg said Facebook expects to be "fully compliant" with tough new EU new laws, called GDPR, on the use and protection of personal data.
The data protection law goes into force on Friday.
"We do expect to be fully compliant on May 25, so in three days," Zuckerberg said.
It will give Facebook's European users - estimated at around 252 million people - more control over what companies can do with what they post, search and click, regardless of what country those companies operate in. Companies could be fined up to 4 percent of their worldwide annual turnover for violations.
Zuckerberg calls regulation "important and inevitable"
2:09 p.m. ET: Mark Zuckerberg said that regulation was "important and inevitable" but that it should be done "right."
"I don't think the question here is whether or not there should be regulation," he said. "I think the question is what is the right regulation. I think the internet is becoming increasingly important in people's lives. Some sort of regulation is important and inevitable, and the important thing is to get it right and to make sure that we have regulatory frameworks that help protect people but are flexible so that they allow for innovation that don't inadvertently prevent new technologies like AI from being developed."
Zuckerberg: Millions of fake accounts taken down this year
1:47 p.m. ET: Mark Zuckerberg said that Facebook has taken down about 580 million fake Facebook accounts within the first quarter of this year.
He said that the "vast majority" of the fake accounts were taken down "within minutes" of being registered.
Zuckerberg: Artificial intelligence flagging terror content
1:38 p.m. ET: After hearing European lawmakers ask questions for around 30 minutes, Mark Zuckerberg said that the platform's artificial intelligence system has flagged 99 percent of content linked to al Qaeda and the Islamic State of Iraq and Syria, or ISIS.
Regarding interference in elections, the Facebook CEO said that there was "an arms race" between the company and "our adversaries," which have access to some of the same artificial intelligence tools that Facebook does.
"We'll never be perfect on this," Zuckerberg said.
Zuckerberg: Over 200 apps suspended from Facebook
12:47 p.m. ET: Mark Zuckerberg said that Facebook has suspended more than 200 apps from its platform in the wake of the Cambridge Analytica scandal.
The Facebook CEO also told European lawmakers that the company has investigated thousands of apps after concerns were raised about them.
Zuckerberg: Facebook investing in security
12:41 p.m. ET: Mark Zuckerberg said that Facebook would hire 20,000 people to work on safety and security by the end of the year.
"On top of the investments that we're making in other areas, I expect that these increased investments in security will significantly impact our profitability," Zuckerberg said. "But I want to be clear: Keeping people safe will always be more important than maximizing our profits."
Mark Zuckerberg: "We haven't done enough"
12:36 p.m. ET: Mark Zuckerberg apologized to European lawmakers for not doing enough to protect Facebook users' data, saying "we haven't done enough to prevent these tools from being used for harm."
"That goes for fake news, foreign interference in elections and developers misusing people's information," Zuckerberg said. "We didn't take a broad enough view of our responsibility, and that was a mistake, and I'm sorry for it."
What is Mark Zuckerberg expected to say?
11:54 a.m. ET: Mark Zuckerberg plans to apologize for not taking a broad enough view of Facebook's responsibilities, a source told CBS News.
The Facebook CEO is expected to discuss action the company has taken against Cambridge Analytica, according to a source with knowledge of Zuckerberg's remarks.
Cambridge Analytica is the controversial, now-shuttered British political consulting firm whose use of Facebook data during the 2016 American presidential election and the U.K. "Brexit" referendum has led to multiple investigations.
Zuckerberg was also expected to discuss Facebook's efforts to protect election integrity and seek to emphasize the importance of Europe to the company.