WASHINGTON/SAN FRANCISCO - Facebook Inc Chief Executive Mark Zuckerberg on Tuesday navigated through the first of two US congressional hearings without making any further promises to support new legislation or change how the social network does business.

During nearly five hours of questioning by 44 US senators, Zuckerberg repeated apologies he previously made for a range of problems that have beset Facebook.

But the 33-year-old internet mogul managed to deflect any specific promises to support any congressional regulation of the world's largest social media network and other US internet companies.

"I'll have my team follow up with you so that way we can have this discussion across the different categories where I think this discussion needs to happen," Zuckerberg told a joint hearing by the US Senate's Commerce and Judiciary committees, when asked what regulations he thought were necessary.

Investors were impressed with his performance. Shares in Facebook posted their biggest daily gain in nearly two years, closing up 4.5 percent.

The shares fell steeply last month after it came to light that millions of users' personal information was harvested from Facebook by Cambridge Analytica, a political consultancy that has counted US President Donald Trump's election campaign among its clients. The latest estimate of affected users is up to 87 million.

That disclosure pitched Facebook into a crisis of confidence among users, advertisers, employees and investors who were already struggling with Facebook's reaction to fake news and its role in the 2016 election.

Reuters