Briant, who interviewed the group's employees for her academic research, said she was "compelled" by the U.K. Electoral Commission, the Information Commissioner's Office and the committee to discuss "Cambridge Analytica's grossly unethical conduct enacted for profit", according to evidence released on Monday.
Ms Kaiser worked with Mr Banks on the Leave.EU campaign and has claimed to MPs that the group used data from UKIP members, Eldon Insurance and the tycoon's GoSkippy Insurance firm to swing the poll.
Banks told Reuters the testimony was "sheer whoppers", a British colloquialism for lies.
But Brittany Kaiser, who left Cambridge Analytica in March 2018, has become a whistleblower in the campaign to discredit Britain's vote to withdraw from the EU.
Kaiser also said that Banks refused to pay a bill of 41,500 pounds ($59,500) for initial work undertaken by Cambridge Analytica.
In transcripts of interviews that the United Kingdom parliamentary panel published, Nigel Oakes, the founder of Cambridge Analytica's parent company SGL Group, said the consultancy would have worked with Leave.EU had it been chosen as the official campaign for Britain to leave bloc.
Mr Banks, who funded UKIP for a number of years leading up to the European Union referendum, said via a spokesman: "The fabrications are astonishing".
"It had nothing to do with the referendum campaign" he said.
"Leave.EU benefited from their work with Cambridge Analytica before the decision was made on which Leave campaign would receive the official designation for the referendum", said Damian Collins, the head of the Digital, Culture, Media and Sport Committee.
Trump Reveals Direct North Korea Contacts
The April 27 meeting will only be the third summit between the rivals since the end of the 1950-53 Korean War. The U.S. itself is pushing for the release of three Americans.