U.S. technology giants including Facebook, Twitter, Microsoft, and Google's YouTube could face new laws forcing them to deal with online hate speech if they don't tackle the problem themselves, the European Commission warned.

In May, the four U.S. firms unveiled a "code of conduct" drawn up in conjunction with the Commission, the European Union's executive arm, to take on hate speech on their platforms. It involved a series of commitments including a pledge to review the majority of notifications of suspected illegal hate speech in less than 24 hours and remove or disable access to the content if necessary. Another promise was to provide regular training to staff around hate speech.

But six months on, the Commission is not happy with the progress. EU Justice Commissioner Vera Jourova has commissioned a report, set to be released later this week, which claims that progress in removing offending material has been too slow.

"In practice the companies take longer and do not yet achieve this goal. They only reviewed 40 percent of the recorded cases in less than 24 hours," a Commission official said.

"After 48 hours, the figure is more than 80 percent. This shows that the target can realistically be achieved, but this will need much stronger efforts by the IT companies."