调查人员进入剑桥分析英国总部

British investigators have entered the London offices of the data research firm Cambridge Analytica, which is at the center of controversy over the alleged use of millions of people's personal data from the Facebook social network.

About 20 investigators arrived at the firm's central London offices late Friday, soon after a judge granted a search warrant that Britain's Information Commissioners Office had requested.

Information Commissioner Elizabeth Denham is investigating claims the research firm illegally acquired the personal data from Facebook.

The research firm is alleged to have illegally used the data of an estimated 50 million Facebook users to build profiles for U.S. political campaigns, including the presidential campaign of Donald Trump.