Twitter’s share price sank almost 5 per cent as chief executive Jack Dorsey faced questions from the Senate Intelligence Committee about the spread of misinformation online on Wednesday.

Committee members repeatedly raised the prospect of increased regulation of technology firms including Facebook, Twitter and Google in the session which also discussed privacy protections and how to fight foreign influence on US elections.

“If the answer is regulation,” Senator Richard Burr, the committee’s Republican chairman, said, “let’s have an honest dialogue about what that looks like.”

Facebook, whose chief operating officer Cheryl Sandberg was also appearing in front of the committee, saw its shares fall 1.4 per cent on Wednesday morning.

The Intelligence Committee invited Larry Page, chief executive of Google’s parent Alphabet, or Google boss Sundar Pichai to the hearing but both declined.

Google offered to send chief legal officer Kent Walker as an “appropriate witness" but the committee rejected the proposal.

“Our members have a series of difficult questions about structural vulnerabilities on a number of Google’s platforms that we will need answered,” said Democratic Senator Mark Warner.

“Imagine the damage to the markets if forged communications from the Fed chairman were leaked online,” he said, “Or consider the price of a Fortune 500 company’s stock if a dishonest short-seller was able to spread false information about that company’s CEO – or the effects of its products -- rapidly online?"

Mr Dorsey, who said he had overcome his shyness in order to appear at the hearing, read his opening statement from his mobile phone while live tweeting.

“When I think of our work, I think of my mom and dad in St. Louis, a Democrat and a Republican,” Mr Dorsey said.

“For them Twitter has always been a source of joy, learning and connection to something bigger.”

Twitter has faced criticism from some right-wing activists who claim that the platform has censored their controversial message.

In an apparent response to that criticism Mr Dorsey said: “We believe people will learn faster by being exposed to a wide range of opinions and ideas.

"We aren’t proud of how that free and open exchange has been weaponised and used to distract and divide people, and our nation."

Ms Sandberg faced questions about Facebook's use of personal data to sell adverts, to which she responded that "privacy and advertising aren't at odds. In fact they go together."