Britain's information regulator says it is assessing evidence gathered from a raid on the office of data firm Cambridge Analytica, carried out as part of an investigation into alleged misuse of personal information by political campaigns and social media companies.

More than a dozen investigators from the Information Commissioner's Office entered the data firm's central London office late Friday, shortly after a High Court judge granted a warrant. The investigators were seen leaving the premises early Saturday.

The regulator said it will "consider the evidence before deciding the next steps and coming to any conclusions."

Cambridge Analytica, known for working on President Donald Trump's 2016 campaign, is being investigated over whether it improperly used data from around 50 million Facebook users to target voters with ads and political messages.