Second-hand clothing platform Vinted is under investigation in France after some user accounts were found to be directing visitors to pornographic content.
France's Children's Rights Commissioner Sarah El-Haïry said she had asked watchdog Arcom to examine the allegations first reported in French media.
Vinted, which has 23 million users in France, has no age-verification procedure - meaning children and teenagers could have been exposed to pornographic material without having to show proof they were over 18.
In a statement, the Lithuania-based company said it had a "zero-tolerance policy regarding unsolicited communications of a sexual nature or the promotion of sexual services".
"All inappropriate and illegal content is removed, and where necessary we take measures against users, including blocking them definitively from our site," it said.
