The EU has opened an investigation into Google over its artificial intelligence (AI) summaries which appear above search results.
The European Commission said it would examine whether the firm used data from websites to provide this service - and if it failed to offer "appropriate compensation" to publishers.
It is also investigating how YouTube videos may have been used to improve its broader AI systems, and whether content creators were able to opt-out.
A Google spokesperson said the probe "risks stifling innovation in a market that is more competitive than ever".
"Europeans deserve to benefit from the latest technologies and we will continue to work closely with the news and creative industries as they transition to the AI era," they said.
The EU's investigation will also cover Google's AI Mode, which gives people an answer in a conversational style with some links to other pages.
It is in addition to the tech giant's existing search platform - providing an experience similar to its rivals such as ChatGPT.
Google's introduction of its AI Overview summaries was met with concerns it could result in fewer visitors to websites.
Without people clicking on web pages, sites generate less money from advertising.
The Daily Mail previously claimed the number of people who clicked its links from Google search results fell by around 50% since Google introduced its AI Overview feature.
The Commission said it was concerned both web publishers and YouTube video creators were not being compensated or given the opportunity to opt-out of their content being used to train the company's AI models.
Ed Newton-Rex from AI fairness campaigners Fairly Trained said it was "career suicide" for people to not publish their work on YouTube or online.
He told the BBC Google "essentially makes it a condition" of online publishing that the firm can "use your work to build AI that competes with you".
"This investigation could not come at a more critical time for creators around the world," he said.
And the move was also welcomed by Rosa Curling, co-executive director of campaign group Foxglove - which had called on the Commission in June to tackle the impact of AI Overviews on independent media organisations.
But she said "clear and present" dangers to journalism and democracy remain.
"We need an urgent opt out for news publishers to stop Google from stealing their reporting today – not when this investigation is finished," she said.
"Otherwise, there will be little left, by the time the Commission is ready to act."
The Commission's investigation comes down to whether Google has used the work of other people published online to build its own AI tools which it can profit from.
Its generative AI systems are capable of producing text, images and video in seconds, in response to simple text prompts.
Many firms can now do this - and they have used huge volumes of online web content to train their underlying systems.
But creatives have voiced concern their work may have formed the basis for big tech's AI products and outputs, at the expense of their own rights or livelihoods.
"A free and democratic society depends on diverse media, open access to information, and a vibrant creative landscape," said Commission executive vice-president Teresa Ribera.
She said AI was ushering in "remarkable innovation" and "many benefits for people and businesses" - but its growth should not come at the cost of the EU's values.
But the Commission's recent enforcement of its tough digital rules - which can see tech companies face huge fines if they found to be breaching them - has been met with outrage from US lawmakers.
Elon Musk's platform X axed the Commission's account for placing adverts on the site, after the EU brandished a €120m (£105m) fine over its blue verification badges.