Facebook, Google and Twitter must do more to tackle fake news or face regulatory action, the European Commission said on Tuesday.

The threat by the EU executive came a year after the U.S. tech giants together with Mozilla, Microsoft and seven European trade bodies signed up to a voluntary code of conduct to combat fake news in a move aimed at warding off intrusive rules.

The Commission is now drawing up regulations known as the Digital Services Act. This will set out liability and safety rules for digital platforms, services and products, a move which has already triggered fears in the tech industry of heavy-handed intervention.

The latest monthly report from the companies showed a wide divergence between them and provided few details on the impact of the measures taken by the companies, EU Justice Commissioner Vera Jourova, EU security chief Julian King and EU digital commissioner Mariya Gabriel said in a joint statement.

"Large-scale automated propaganda and disinformation persist and there is more work to be done under all areas of the Code. We cannot accept this as a new normal," they said.

They called on the companies to cooperate with more independent bodies. An independent consultant hired by the Commission will publish its assessment early next year, followed by the EU executive's own study.