TikTok could be forced into changes to make the app less addictive to users after the EU indicated the platform had breached the bloc’s digital safety rules.

The EU’s executive arm said in a preliminary ruling that the popular app had infringed the Digital Services Act (DSA) due to its “addictive design”.

The European Commission said TikTok, which has more than 1 billion users worldwide, had not adequately assessed how its design could harm the physical and mental wellbeing of users including children and vulnerable adults.

By constantly “rewarding” users with new content, the Chinese-owned platform fuelled constant scrolling and shifted the brains of users into “autopilot mode”, the commission added, which could lead to compulsive behaviour and reduce users’ self-control.

The preliminary ruling accused TikTok of ignoring indicators of compulsive use, such as the amount of time children spend on the app at night.

The commission said it was considering forcing changes to the app’s design, including alterations to its powerful algorithm that pushes content to users.

“At this stage, the commission considers that TikTok needs to change the basic design of its service,” it said in a statement. “For instance, by disabling key addictive features such as ‘infinite scroll’ over time, implementing effective ‘screen time breaks’, including during the night, and adapting its recommender system.”

The commission said TikTok’s safety regime appeared to be inadequate, singling out the screentime management and parental control tools as not doing enough to mitigate the risks created by the app’s addictive design. The screentime management features were too easy to dismiss and parental controls were time-draining to install, the preliminary ruling added.

The commission said its preliminary views did not prejudge the outcome of the investigation and TikTok would have the opportunity to challenge its findings.

Online safety campaigners have urged politicians to tackle features on social media platforms that encourage users to stay online. The crossbench peer and online safety campaigner Beeban Kidron, a leading voice in the UK debate, has urged the British government to “detoxify the dopamine loops” of addictive social media platforms.

Breaches of the DSA can result in a fine totalling up to 6% of a company’s annual turnover, as well as the imposition of remedies such as an app redesign. TikTok does not publish its revenues, but according to estimates from the World Advertising Research Centre it will post revenues of $35bn (£26bn) this year.

TikTok said it rejected the commission’s findings. “The commission’s preliminary findings present a categorically false and entirely meritless depiction of our platform, and we will take whatever steps are necessary to challenge these findings through every means available to us,” a spokesperson for the company said.

Last year Elon Musk’s X was fined €120m (£104m) for a breach of the DSA in the first-ever fine under the legislation. The breaches included what the EU said was a “deceptive” blue-tick verification badge given to users, and impeding research around what adverts the platform had hosted.