Online retail platforms Shein, Temu, AliExpress and Wish are being investigated in France for alleged rule breaches that include minors being able to access pornographic content via their marketplaces, the Paris prosecutor said on Tuesday.

China's Shein will open its first-ever permanent shop in the BHV department store in central Paris on Wednesday, but French Finance Minister Roland Lescure threatened a countrywide ban of the brand after a consumer watchdog spotted child-like sex dolls sold on its marketplace.

Shein spokesperson for France Quentin Ruffat told RMC radio on Tuesday that the company would do everything in its power to collaborate with the investigation, including sharing the names of vendors and buyers of the dolls, which it has now banned.

Ruffat later told BFM TV that the dolls had been on sale since October 16.

"We are in the process of sacking all the offending vendors from the platform," he said.

AliExpress told Reuters that similar listings had been removed from its site and that sellers who violate the platform's policies will be penalised.

A Temu spokesperson said that accusations against the company were connected to minors accessing certain products on its platform.

Wish did not respond to a request for comment.

Probe follows consumer watchdog complaint

The Paris prosecutor's office said it received a complaint from the consumer watchdog known as DGCCRF and referred the case to the National Office for Minors to investigate.

The companies are being investigated on suspicion of disseminating violent, pornographic or degrading messages accessible to minors, which can lead to up to three years in prison and a fine of 75,000 euros ($87,465) for individuals involved, the office said.

Shein and AliExpress are also being investigated over the alleged dissemination of images or representations of minors of a pornographic nature, which can lead to five years in prison and a fine of 75,000 euros, the prosecutor's office said.

Shein pulled the dolls from its website on Sunday, and on Monday imposed a total ban on sex dolls and suspended the "adult products" category on its platform.