Online retailer Temu has filed a lawsuit against fashion giant Shein, alleging “mafia-style intimidation” of suppliers.

A lawsuit was filed in Washington DC on Wednesday, which included claims that Shein “falsely imprisoned” Chinese suppliers for hours by summoning them to its offices, after believing the suppliers were working for Temu.

It also alleged the suppliers had their mobile phones confiscated while held at Shein’s offices and that they were threatened with sanctions for doing business with its rival.

Shein is also accused of misusing intellectual property laws and taking Temu’s marketing and advertising staff.

The lawsuit follows other legal battles between the two Chinese retailers. They both tried to sue each other in US courts last year, before withdrawing their cases in October.

Shein had alleged Temu worked with influencers to discredit it on social media, while Temu filed a lawsuit against Shein for violating antitrust laws.

A Temu spokesperson said: “We sued Shein because recently their actions have escalated. They began to illegally detain merchants, forcibly asking for their phones, stealing our merchant accounts and passwords, stealing our business secrets, and simultaneously forcing merchants to leave our platform.”

A spokesperson for Shein said: “We believe this lawsuit is without merit and we will vigorously defend ourselves.”