Cambridge Analytica CEO Alexander Nix has been questioned by MPs on the Digital, Culture, Media and Sports Committee over the company’s involvement in both Brexit and the US election.

Concerns have been raised over the firm’s profiling and targeting of citizens during political campaigns.

Nix has denied working with the Leave.EU campaign and asserted that the techniques used by his company are similar to practices used within advertising. However some have said these contradict previous statements by the CEO.

The company purchases data about users’ digital footprints – like health information and buying habits – and combines it with psychographics for ‘micro-targeting’. It says it has up to five thousand data points on every adult in the US.

Nix has said that the methods used by Cambridge Analytica during the Trump campaign have also been used in President Obama's election campaign and that Hillary Clinton also employed "hundreds of data scientists".

"I think people see our work as negative because the client is polarising," he told MPs.

"This is about micro-targeting voters and the techniques have been used in advertising for decades. We have taken their best practices and replicated them for a political party.

"We match data with large quantitative research that asks audiences for their preferences, and collate it to micro-target people.

"There is a misunderstanding of what we do. We use data and technology to engage with voters in a more informed and relevant way. That can only be good for politics and democracy."

In a statement issued before the committee meeting Nix said: "Cambridge Analytica had no involvement in the referendum, was not retained by any campaign, and did not provide any services (paid or unpaid) to any campaign."

Privacy experts believe the case could be a turning point in the collection and use of user data in the UK by marketing firms.