Germany pledges 'strict' laws after Facebook data breach

"We'll need much tighter supervision of companies like Facebook", she added.

She spoke after meeting Richard Allan, the head of the US social media firm's public policy for Europe, but she said that his "promises were not enough" to satisfy authorities.

Barley added that firms like Facebook should tell users in "clear, precise and simple language" how their data will be used, and described what happened at the US firm as "intolerable".

She spoke after revelations that UK consultancy firm Cambridge Analytica used a bogus questionnaire to obtain detailed information on 50 million Facebook users. About 2,700 people out of the 270,000 who took part in the questionnaire were from Europe.

Cambridge Analytica then used that information to target what it called people's "inner demons" with fake news updates in order to help Donald Trump in the 2016 US election.

Germany's tough line was echoed by Vera Jourova, the EU's justice commissioner.

"Have any data of EU citizens been affected by the recent scandal? If this is the case, how do you intend to inform the authorities and users about it?", she wrote in a letter to Facebook's chief operating officer, Sheryl Sandberg, seen by the Reuters news agency.

She asked Sandberg if a similar situation could "not be repeated today" and if Facebook thought stricter rules were needed for social media firms "like those that exist for traditional media".

She also said "disappointed" in Facebook's boilerplate reactions to the data breach so far.

"Trust is now diminished," Jourova said.

A new EU law that comes into force later this year will fine firms four percent of global turnover for similar breaches, but this would not be retrospective on Facebook.

A German law already punishes social media firms with up to €50m fines if they do not take down posts or ads containing hate speech.

Jourova gave Facebook two weeks to answer her letter and urged it to cooperate with British data authorities in their investigation of the Cambridge Analytica affair.

Germany has played a lead role in EU privacy legislation in part due to its traumatic legacy of the East German police state during the Cold War.