ChatGPT will have to comply with tougher safety rules after the EU added it Monday to a list of digital services subject to greater legal scrutiny in Europe, a first for an AI chatbot.

Brussels also designated the Reddit forum and the popular gaming network Roblox as "very large" online platforms, a label that comes with additional obligations and oversight.

"ChatGPT, Reddit and Roblox will now be held to a higher standard of scrutiny and accountability in the European Union, in line with their large impact on our citizens and society," EU technology chief Henna Virkkunen said.

The "very large" designation applies to platforms and search engines with more than 45 million monthly active users in the 27-nation bloc, a threshold ChatGPT, Reddit and Roblox reported meeting, the commission said.

The three now have four months to comply with additional obligations under the Digital Services Act (DSA), a content law that is a major weapon in the legal armoury the EU has deployed to rein in Big Tech in recent years.

These include "assessing and mitigating" risks related to "the dissemination of illegal content, the negative effects on minors, users' physical and mental well-being, fundamental rights, electoral processes and public
security," Brussels said.

To bring it under the DSA's regulatory umbrella, the commission qualified ChatGPT as a search engine.

'Proud'
The hugely popular artificial intelligence chatbot developed by US company OpenAI reported more than 159 million users in the EU at the end of March, representing over a third of the bloc's population.

ChatGPT said it was "preparing to meet the additional compliance requirements" that came with the designation, while Roblox said it was "proud to be the first gaming platform" to gain the "very large" label in the EU.

"Safety is foundational to everything we do and we look forward to continuing our constructive engagement with the European Commission," said the US-based platform's general manager for Europe, Joost Hagesteijn.

Hugely popular with children and known for its immersive world of colourful graphics, Roblox says it has 46.6 million active players in the EU, just above the DSA threshold for tougher scrutiny.

The sprawling US discussion platform Reddit says it has more than 57 million users in the bloc.

Heavy fines
The designations come as the EU has stepped up regulatory enforcement against the world's biggest digital platforms, including many American ones, despite strong US pushback and threats of retaliation.

The EU has separately adopted the world's most far-reaching rules to govern artificial intelligence. Its flagship AI Act entered into force in 2024, with obligations kicking in over several years to curb potentially dangerous uses of the technology.

Lena-Maria Boswald, of the German tech think tank Interface, said ahead of ChatGPT's designation that the expected move would set a "precedent" and "influence the regulatory expectations for every large generative AI system used in the EU".

"OpenAI already has risk-management obligations under the AI Act, but the DSA could widen the scope," she said.

Around 30 services have been listed for extra scrutiny under the DSA, most of them owned by major technology companies such as Google, Apple, Microsoft, TikTok, X, Amazon and Shein. The list also includes several porn sites and the collaborative online encyclopedia Wikipedia.

Companies found in breach of the law face heavy penalties, including fines of up to six percent of their annual global turnover and, in cases of serious and repeated violations, a possible ban on operating in Europe.

The EU recently told TikTok to change what it deemed its addictive design or face large DSA fines.

To date, the bloc has hit three firms with penalties under the law: shopping giants Temu and AliExpress, and Elon Musk's social media platform X, which was handed a 120-million-euro ($138 million) fine for transparency and other violations.