Facebook will introduce new measures to improve transparency around advertising in Britain and require political ads to be clearly label led, an executive said on Thursday, as he faced questions in Parliament over a data scandal.

Facebook has said the personal information of about 87 million users might have been improperly shared with political consultancy Cambridge Analytical, which worked on Donald Trump's 2016 presidential election campaign.

Facebook Chief Technology Officer Mike Schroeder faced a day of questioning from a panel of British lawmakers in London, where he apologized for the firm's failings over data protection and sometimes looked uncomfortable as he was unable or unwilling to answer all their questions.