All four signed an EU code of conduct in May aimed at combatting internet hate speech.
"It is our duty to protect people in Europe from incitement to hatred and violence online," European commissioner for justice, consumers and gender equality Vera Jourova said.
"This is the common goal of the code of conduct. The last weeks and months have shown that social media companies need to live up to their important role and take up their share of responsibility when it comes to phenomena like online radicalisation, illegal hate speech or fake news.
The four IT companies had committed to review notifications of potential hate speech within 24 hours.
But the Commission noted in a report published today that among 600 notifications made, only 28 per cent led to the removal of content while just 40 per cent were treated within 24 hours.
Another 43 per cent were reviewed in under 48 hours.
The notifications were sent to the IT companies by a group of 12 NGOs from nine different countries who analysed notification responses over a six week period.
YouTube was also most active in removing content on 48 percent of cases compared to Twitter's 19 per cent.
Facebook reviewed 50 per cent of cases within a day and removed content on 28 per cent of notifications. Microsoft did not receive any notifications.
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