Brussels has warned Elon Musk that Twitter must comply with the EU’s new digital rules under his ownership, or risk hefty fines or even a ban, setting the stage for a global regulatory battle over the future of the social media platform.

Thierry Breton, the EU’s commissioner for the internal market, told the Financial Times that Elon Musk must follow rules on moderating illegal and harmful content online after Twitter accepted the billionaire’s $44bn takeover offer.

Breton said: “We welcome everyone. We are open but on our conditions. At least we know what to tell him: ‘Elon, there are rules. You are welcome but these are our rules. It’s not your rules which will apply here.’”