The U.K.'s telecommunications regulator Ofcom said on Monday it launched a formal investigation into Elon Musk's X over its AI chatbot Grok's image creation feature that has been increasingly used to produce sexualized deepfakes.

Grok is facing growing international backlash for allowing users to create and share sexualized pictures of women and children using simple text prompts.

Ofcom described the reports as "deeply concerning."

It said in a statement that the undressed images of people "may amount to intimate image abuse or pornography – and sexualized images of children ... may amount to child sexual abuse material."

Ofcom said it had contacted X on Jan. 5, asking it to explain the steps it has taken to protect U.K. users.

Without sharing details of the exchange, the regulator said that X did respond within the given timeframe.

The formal investigation will determine whether X "failed to comply with its legal obligations."

Under Britain's Online Safety Act, which came into force in July, websites, social media and video-sharing platforms hosting potentially harmful content are required to implement strict age verification through tools such as facial imagery or credit card checks.

It is also illegal for media sites to create or share non-consensual intimate images or child sexual abuse material, including sexual deepfakes created with AI.

Ofcom has the power to impose fines of 10% of worldwide revenue for breaches of these rules.

Grok appeared to deflect the international criticism with a new monetization policy at the end of last week, posting on X that the tool was now "limited to paying subscribers," alongside a link to a premium subscription.

U.K. Prime Minister Keir Starmer has condemned the move as an affront to victims and "not a solution."

On Saturday, Indonesia became the first country to deny all access to the tool, with Malaysia following suit on Sunday.

The European Commission also said it was reviewing complaints about Grok.