Mark Zuckerberg is facing questions about claims of a huge data breach

The founder of Facebook has told US senators that his company in an “arms race” with Russia.

Mark Zuckerberg's been giving evidence to American politicians after as many as 87m users of the social network had their data harvested by Cambridge Analytica, a firm working on the Trump 2016 election campaign.

Although he faced little direct questioning about Russian election meddling, he did claim he was in an "arms race" with the nation.

Facebook CEO Mark Zuckerberg testifies at a joint hearing of the Senate Judiciary and Commerce committees, 22-04-2018. Image: Ting Shen/Xinhua News Agency/PA Images

He admitted it is "entirely possible" that the data improperly obtained by Cambridge Analytica could have been used by the Kremlin-linked troll factory - the Internet Research Agency – in an attempt to influence the US Presidential election in 2016.

"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.

"So this is an arms race.

"They're going to keep getting better at this, and we need to invest in making sure we keep getting better at this too.

"Which is why we are going to have more than 20,000 people, by the end of this year, working on security and content review across the company."

He later added: "As long as there are people in Russia whose job it is to interfere with elections around the world, this is going to be an on-going conflict."