Facebook CEO Mark Zuckerberg told senators Tuesday that his company had been in communication with special counsel Robert Mueller’s office in relation to Russian meddling in the US election.

Under questioning from Vermont Democratic Sen. Patrick Leahy, Zuckerberg replied, “Yes,” before clarifying that he personally was not interviewed but that his employees were.

“I want to be careful here, because our work with the special counsel is confidential and I want to make sure in an open session I’m not revealing something that’s confidential.”

He also said that one of his biggest regrets was not identifying Russian interference in the 2016 election.

“One of my greatest regrets in running the company is that we were slow in identifying the Russian information operations in 2016,” he said in testimony before a joint hearing of the Senate Judiciary and Commerce committees.

“We expected them to do a number of more traditional cyberattacks, which we did identify. But we were slow” detecting “new operations,” he added in response to a question from California Democratic Sen. Diane Feinstein.

Zuckerberg, who earlier apologized to users of the social media platform for not protecting their privacy, told senators Tuesday that his company was committed to safeguarding users privacy.

“It’s not enough to just give people a voice. We need to make sure that people aren’t using it to harm other people or spread misinformation and not enough to give people control over their information, we need to make sure that the developers they share it with protect their information, too,” he said.

“Across the board, we have a responsibility to not just build tools, but to make sure that they are used for good. It will take some time to work through all the changes we need to make across the company.”

But he also defended Facebook as a source for good in the world.

“As Facebook has grown, people everywhere have a powerful new tool for staying connected to the people they love, for making their voices heard and for building businesses and communities,” he said.

“Just recently we have seen the #MeToo movement and March for Our Lives organized at least in part on Facebook. After Hurricane Harvey people came together to raise money for relief.”

At the outset, North Dakota GOP Sen. John Thune slammed Zuckerberg over the data breaches in his opening statement.

“The idea that every person who decided to try an app, information about nearly 300 other people was scraped from your services, to put it mildly, disturbing,” he said, warning that lawmakers could beef up regulation of social media.

“And the fact that those 87 million people may have technically consented to making their data available, doesn’t make most people feel any better.”

Florida Democratic Sen. Bill Nelson issued a blunt warning during his opening statement.

“Let me just cut to the chase. If you and other social media companies do not get your act in order, none of us are going to have any privacy anymore.”

Outside the Capitol, the online protest group Avaaz set up 100 life-sized cutouts of Zuckerberg wearing T-shirts with the words “Fix Facebook” on them.

Zuckerberg visited with senators in closed-door meetings Monday, previewing the public apology he planned to give Congress on Tuesday after revelations that Cambridge Analytica, a data-mining firm affiliated with Donald Trump’s presidential campaign, gathered personal information from 87 million users to try to influence elections.

With Post wires