The Guardian UK: In a TikTok video a young girl – her age anywhere between 10 and 15 – sits unboxing package after package of products she says were sent to her by skincare brands. She calls it a “PR haul”.

In another video, a 16-year-old opens a box of products she received from a well known brand. She says: “I know I have younger people watching,” before reading out a note from the brand that says: “Can’t wait for you to share your thoughts.”

This is the rapidly growing world of children’s skincare, in which online influencers as young as 13 accept free products from brands and promote them to their followers. This is despite warnings from dermatologists that children don’t need most skincare products and concern from regulators that the practice exists in a legal grey area.

The Italian Competition Authority (AGCM) is investigating the beauty brands Benefit and Sephora after they appeared to adopt a “particularly insidious” strategy of using young influencers to market skincare to children.

The AGCM launched an investigation into the brands’ owner, the luxury goods company LVMH, for possibly attempting to sell anti-ageing treatments to children younger than 10.

It said the companies “may have failed to make clear” the cosmetics they sold were not intended for children, while “appearing instead to have encouraged their purchase through covert marketing strategies involving young micro-influencers”.

LVMH said that it, Sephora and Benefit would “fully cooperate with the authorities” but declined to comment further. “All the companies reaffirm their strict compliance with applicable Italian regulations,” it added.

An investigation by the Guardian found numerous videos of young people thanking brands for products they had received. It identified ambassador programmes open to children as young as 13, offering free products in exchange for promotional content online. However, the terms of these arrangements sit in a murky legal area.

The US skincare brand Evereden, for example, runs a scheme with no official age limit given, simply saying it loves “all ages and all stages” and promising those who are accepted early access to new products. Some of the influencers the Guardian found linked to the brand appeared to be aged 12.

Those under 18 have to get parental permission to join. The brand says young “aspiring influencers” can get free monthly PR and event invites. Ambassadors receive free products and get early access to new launches. In another Evereden video on TikTok, viewers are told they can play games with the brand, answer questions and earn coins that can be spent on “goodies” sold in its shop.

Evereden did not respond to attempts to contact it for a comment. It did not clarify the age at which people can be accepted on to its ambassador programme.

On its website, asked whether it works with influencers under 18, it says: “Yes! As a kids’ brand, we want to partner with our actual audience, as well as their parents and guardians. We think it’s important for kids to see people like them taking care of their skin and being empowered by age-appropriate self-care routines. However, we are committed to engaging with young creators in a responsible and ethical manner, and we require parental or guardian consent in all collaborations.”

The youth skincare brand Bubble calls for ambassadors who are aged 16 or over in a similar scheme, which previously accepted children as young as 13........