The secretive data company cofounded by Facebook board member Peter Thiel has been dragged into the widening Facebook data scandal, with the Cambridge Analytica whistleblower claiming "senior Palantir employees" were given access to the data firm's controversial data set.

Christopher Wylie has alleged Cambridge Analytica used the Facebook friends data of up to 50 million people without the users' permission.

At a marathon Commons select committee hearing in London on Tuesday, Wylie claimed Palantir — which counts the NSA and GCHQ among its clients — was also brought in and given access to the data. Palantir denied the allegations.

"We actually had several meetings with Palantir whilst I was there. ... There were senior Palantir employees that were also working on the Facebook data," Wylie said.

"That was not an official contract between Palantir and Cambridge Analytica but there were Palantir staff that would come into the office and work on the data."

"We’d also go meet with Palantir staff at Palantir."

"Palantir didn’t officially contract with Cambridge Analytica , but there were Palantir staff who’d help build the models that we were working on."