Mark Zuckerberg has apologised to a Senate Committee and admitted the Russian interference in the 2016 election is one of his “greatest regrets.”

The Facebook founder came before a joint hearing of the Senate Judiciary Committee and Senate Commerce Committee in light of the recent Cambridge Analytica scandal that has plagued the company.

Switching his signature grey t-shirt for a dark suit, Zuckerberg was probed by Senators on Facebook and its approach to privacy, as well as the impact it had on the 2016 Presidential election.

First up, Zuckerberg took time to apologise for the recent data sharing controversy.

“Facebook is an idealistic and optimistic company,” he told the committee. “For most of our existence, we focused on all of the good that connecting people can do.”

“But it's clear now that we didn't do enough to prevent these tools from being used for harm, as well.

“And that goes for fake news, for foreign interference in elections, and hate speech, as well as developers and data privacy.

“We didn't take a broad enough view of our responsibility, and that was a big mistake. And it was my mistake. And I'm sorry. I started Facebook, I run it, and I'm responsible for what happens here.”

Getting political

Republican nominee from the 2016 election, Senator Ted Cruz, grilled Zuckerberg on Facebook’s political alignment.

“Do you consider yourself a neutral public forum, or are you engaged in political speech, which is your right under the First Amendment,” Cruz asked Zuckerberg.

“Well, senator, our goal is certainly not to engage in political speech,” Zuckerberg replied.

“I am very committed to making sure that Facebook is a platform for all ideas.

“We're proud of the discourse and the different ideas that people can share on the service, and that is something that, as long as I'm running the company, I'm going to be committed to making sure is the case.”

Cruz cited Facebook’s removal of a popular Trump government advocacy page, as well as posts from a Fox News reporter, explaining to Zuckerberg, “that appears to be a pervasive pattern of political bias.”

The Russian “arms race”

From the other side of politics, Zuckerberg was questioned by Democrat Senator, Dianne Feinstein, on Russia’s exploitation of Facebook and the impact it had on 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,” Zuckerberg confessed.

This was with reference to the fake accounts and group pages that gathered hundreds of thousands of followers during the election campaign.

“There are people in Russia whose job it is -- is to try to exploit our systems and other internet systems,” he said.

“So, this is an arms race, right? I mean, they're going to keep on getting better at this, and we need to invest in keeping on getting better at this, too, which is why one of things I mentioned before is we're going to have more than 20,000 people, by the end of this year, working on security and content review across the company.”