Whistleblower at center of privacy scandal, testifies in U.K.

LONDON (CBSNews) -- The whistleblower at the heart of the Facebook privacy scandal is testifying before British lawmakers investigating the increasing rise of fake news. Christopher Wylie has alleged that Cambridge Analytica harvested details of 50 million Facebook users and used the material in U.S. President Donald Trump's 2016 election campaign.

It is alleged the material made it possible to micro-target users with campaign material.

At a news conference on Monday on a linked issue, Wylie declined to answer questions about whether the data was also used in Britain by the campaign to leave the European Union. He said he would discuss the matter when he spoke to lawmakers from Parliament's media committee on Tuesday.

In the U.S. Wylie agreed to Democrats' requests that he testify before and provide documents to the committee.

Democrats had struck a defiant stance after Republicans' announcement last week. A lawyer for Wylie confirmed to CBS News that Wylie would appear and that the committee had been duly informed of his intention to do so. Committee officials said they were expecting both testimony and documents from Wylie in the coming weeks.