• The European Commission, the EU's executive arm, said it was concerned TikTok Lite's "Task and Reward Program" had been launched "without prior diligent assessment of the risks it entails, in particular those related to the addictive effect of the platforms."
• Children are thought to be at risk given the suspected absence of effective age verification mechanisms on TikTok, the EU said.
• A spokesperson for TikTok was not immediately available to comment when contacted by CNBC on Monday.

The European Union on Monday opened proceedings against ByteDance's TikTok and threatened to suspend its newly launched TikTok Lite rewards program, where users can earn points for liking content or inviting friends to the app.

The European Commission, the EU's executive arm, said TikTok had 24 hours to provide a risk assessment report for TikTok Lite or face fines. The social media app was given until May 3 to provide further requested information.

The commission said it was concerned TikTok Lite's "Task and Reward Program" had been launched "without prior diligent assessment of the risks it entails, in particular those related to the addictive effect of the platforms."

Children are thought to be at risk given the suspected absence of effective age verification mechanisms on TikTok, the EU said.

A spokesperson for TikTok told CNBC that the firm was "disappointed" with the decision.

"The TikTok Lite rewards hub is not available to under 18s, and there is a daily limit on video watch tasks. We will continue discussions with the Commission," they added.

The probe represents the second formal proceedings the EU has launched against the social media company. In February, the EU announced it was investigating whether TikTok had broken rules relating to the protection of minors, advertising transparency, and the risk management of addictive design and harmful content.

"Under the Digital Services Act, online platforms have the responsibility to assess and address any potential risks their users may face," EU antitrust chief Margrethe Vestager said in a statement.

"So, the Commission has opened a compliance case that urges TikTok to submit an assessment and provide more information on how it is protecting its users from potential risks on their platform," she added.

What is TikTok Lite?

TikTok Lite, which was launched in France and Spain this month, is a new app with a functionality aimed at users aged 18 years and older.

The app's rewards program allows users to earn points while performing certain tasks, such as watching videos or following creators. These points can then be exchanged for rewards, such as gift cards or Amazon vouchers.

Under the terms of the EU's sweeping Digital Services Act, companies with more than 45 million average active users in the bloc are labeled as very large online platforms and must comply with stringent rules to fight illegal and harmful content on their platforms.

"Endless streams of short and fast-paced videos could be seen as fun, but also expose our children to risks of addiction, anxiety, depression, eating disorders, low attention spans," EU industry chief Thierry Breton said in a statement.

"With our first DSA non-compliance case against TikTok still ongoing, the company has launched TikTok Lite which financially rewards extra screen time. We suspect TikTok 'Lite' could be as toxic and addictive as cigarettes 'light,'" Breton said.

"Unless TikTok provides compelling proof of its safety, which it has failed to do until now, we stand ready to trigger DSA interim measures including the suspension of TikTok Lite feature which we suspect could generate addiction."

Correction: TikTok Lite was launched in France and Spain this month. An earlier version misstated the timing.