Facebook CEO Mark Zuckerberg has appeared before legislators during a joint hearing of the Senate Commerce and Judiciary Committees.

The hearing was called following the data scandal around Facebook and the UK data firm Cambridge Analytica.

During the interview Zuckerberg said that the social media platform is in an arms race with Russia.

“This is an arms race. They're going to keep getting better," he said.

 He also told senators that the special counsel who was investigating alleged Russian tampering in the 2016 US election had interviewed Facebook staff, although he said he has not been interviewed himself.

Zuckerberg told Congress that Facebook is developing new tools to identify fake accounts.

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

“We need to invest in getting better at this too."

The grilling comes against the backdrop of a class action lawsuit filed against Facebook and Cambridge Analytica yesterday for stealing and improperly using more than 70.6 million users' data.

Around 87 million Facebook users had their personal information improperly shared with Cambridge Analytica.

The topic of regulating the social media giant – which has 2.2 billion users – also came up.

Senator John Kennedy said: "I don't want to have to vote to regulate Facebook. But by God, I will. That depends on you... Your user agreement sucks."

Zuckerberg said he would welcome regulation as long as it was the "right regulation” but did not elaborate.

Zuckerberg was also asked whether Facebook has a monopoly, replying that it "doesn't feel like it".