The Competition and Markets Authority said it was ordering Google to give online publishers the option, in what it called a “world first.”

The watchdog is seeking to loosen the U.S. tech giant’s stranglehold on the U.K’s online search market by using new digital powers to force changes to the company’s business practices.

Under the decision, Google will have to give publishers “effective tools” to prevent their content from being used to power the company’s generative artificial intelligence services and its AI search features like AI Overviews and AI Mode.

Google will also have to properly cite publisher content in AI-generated search resulted by using clear links, and let publishers opt out of having their content used to fine-tune AI models.

The watchdog said the decision will give publishers a stronger hand when negotiating content deals with Google. Publishers are defined as anyone who puts content on the web that’s available to people in Britain.

The CMA’s ruling was expected, because it had released draft proposals at the start of the year after using its new digital powers to label Google a “ strategic” player in online search advertising.

It previously found that news publishers had suffered a drop in traffic since Google rolled out its AI Overviews – summaries that appear at the top of some search queries – because fewer users are clicking through to the original articles.

The watchdog said its requirements will also apply to big changes that Google unveiled in May, which further embed AI in the company’s search services.

Google is “engaging with regulators like the UK’s Competition and Markets Authority to ensure website owners have the right tools as user preferences evolve,” the company’s general manager of search ecosystem, Mrinalini Loew, said in a blog post.

“Today, we’re beginning to test a new control that lets website owners manage how their links and content appear in generative AI Search features.”

CMA Chief Executive Sarah Cardell said the measures will result in “fair treatment, greater transparency and meaningful choice for businesses and consumers” and will help tens of millions of British users “better understand and trust the information presented to them.”