BRUSSELS, Dec. 8 -- In a dramatic escalation of its feud with European regulators, Elon Musk's X has terminated the European Commission's advertising account just days after the social media platform was hit with a €120 million (RM574 million) fine for violating the EU's new digital transparency rules.

X's head of product, Nikita Bier, announced the move on the platform early Sunday, posting a screenshot of the terminated account with the message: "Your ad account has been terminated."

According to Politico, the move immediately fuelled a brewing transatlantic trade dispute, with top officials in the Trump administration siding with the US tech company against Brussels.

Bier accused the EU executive of hypocrisy, alleging that it...