Brussels is poised to launch probes into TikTok and YouTube to see what steps they are taking to ensure protection of minors on their platforms, an EU official with knowledge of the matter told AFP on Wednesday.

"The services of EU Commissioner Thierry Breton are preparing to launch additional investigations into platforms' compliance with the DSA regarding the protection of minors," the official said.

The DSA is the Digital Services Act, a new EU law that came into force in August this year and which requires big online platforms to regulate their content to prevent and remove illegal content and disinformation.

Breton has already overseen the launch of three probes last month into TikTok, X (formerly Twitter) and Meta, owner of Facebook, to seek information on "illegal content and disinformation" they may have allowed to circulate relating to the October 7 Hamas attack in Israel.

Now, in relation to child-protection measures, "information requests are on their way for TikTok and YouTube," the EU official said on condition of anonymity.

The official said concerns focus on the measures TikTok, owned by Chinese company ByteDance, and YouTube, part of the Alphabet digital empire that includes Google, use to evaluate and mitigate risks arising from videos shared on their sites when it comes to minors' mental and physical health.

Brussels also wants more information on procedures ensuring the content seen by minors is age-suitable.

Breton said in August that "child protection will be an enforcement priority" for the DSA.

Since the DSA has come into effect, it has also been used to start a probe into AliExpress, the Chinese e-commerce giant owned by Alibaba, to seek more information on what it is doing to protect consumers online from illegal products.

Substantiated infractions of the DSA can carry heavy penalties ranging up to fines of six percent of an online company's global revenue.

The aim of the DSA is to better protect Europeans online.

It started in August by requiring online platforms whose monthly users include more than 10 percent of the EU population, or 45 million people, to have in place mechanisms to quickly pull down content illegal under the laws of the EU or its member states, and to establish risk assessment and mitigation measures.

Nineteen platforms, including Google Search, Facebook, Instagram, TikTok, YouTube, Amazon and Apple's AppStore reached that threshold.

Other smaller online companies will come under DSA scrutiny from mid-February, when EU member states will have set up national supervisory authorities.