The British data analysis company, hired by the 2016 Trump campaign, said the source of the accusations — which it called “a former contractor” — was “misrepresenting himself and the company”.

“This Facebook data was not used by Cambridge Analytica as part of the services it provided to the Donald Trump presidential campaign; personality targeted advertising was not carried out for this client either,” it said in a statement.

According to a joint investigation by The New York Times and Britain’s Observer, the firm was able to create psychological profiles on 50 million Facebook users through a personality prediction app that was downloaded by 270,000 people but also scooped up data from friends.

Facebook has responded by suspending Cambridge Analytica’s account and pledging to probe the allegations, but has pushed back against the claim of a major breach, suggesting misused data was limited to a far smaller group of users.

Its share price plunged on Monday, as officials on both sides of the Atlantic called for investigations.

Elizabeth Denham, Britain’s Information Commissioner who regulates the sector in the country, announced her office would seek a court warrant on Tuesday to search Cambridge Analytica’s computer servers.

She said the company had been “uncooperative” to requests for access to its records and missed a Monday deadline stipulated.

“The information commissioner is seeking a warrant to obtain information and access to systems and evidence related to her investigation,” Denham’s office said in a statement.

It added Facebook had agreed to “stand down” from its own search of the company’s London premises “at the information commissioner’s request”.

“Such a search would potentially compromise a regulatory investigation,” the statement said.

Meanwhile, fresh allegations against senior executives at Cambridge Analytica emerged on Monday evening. 

The company’s chief executive Alexander Nix was secretly filmed by Britain’s Channel 4 News saying it could entrap politicians in compromising situations with bribes and sex workers, using ex-spies to dig up dirt on opponents.

He also said the firm secretly campaigns in elections around the world, including by operating through a web of shadowy front companies, or by using sub-contractors.

A Cambridge Analytica spokesman told the news programme it does not use “untrue material for any purpose”. 

“We entirely refute any allegation that Cambridge Analytica or any of its affiliates use entrapment, bribes, or so-called ‘honey-traps’ for any purpose whatsoever,” the spokesman added. DM