Shein, the world's most widely used shopping platform, has sued e-commerce clothing and accessories platform Temu in a recent issue.

Online fast-fashion platform Shein accused Temu of copyright infringement "on an industrial scale," while Temu countered that Shein is using litigation to stifle competition, as a trial opened at London's High Court on Monday.

The ‌case is part of a global legal battle between the fast-growing rivals, with potential implications for platform practices, supplier relationships, and the enforcement of intellectual property rights across global e-commerce.

Shein's claim:

It comes after Shein alleges Temu used thousands of its photos to advertise copies of Shein's own-brand clothing on its website to "piggyback" on a more established competitor.

"This was an attempt to steal a march on an existing participant in the market that Temu has sought to obtain; we say, an unfair advantage," Shein's lawyer, Benet Brandreth, said.

Temu denies the allegations.

Temu's counter-claim over removed products:

Brandreth told the court Temu has dropped its defense to Shein's copyright claims over nearly 2,300 photos taken by Shein employees, likening it to "the defendant waiting to see if the witnesses will turn up, only to plead guilty."

Temu, owned by ‌PDD Holdings, has counterclaimed, seeking damages after it had to remove thousands of product listings when Shein obtained an injunction.

It also alleges Shein broke competition law by tying fast-fashion suppliers to exclusive agreements. That part of the case is due to go to trial next year.

Temu's lawyers argue Shein's lawsuit is not a legitimate attempt to stop copyright infringement but is designed to secure a competitive advantage.

The two-week London trial is the latest legal battle between the two rivals, which have also sued each other in the U.S., and comes amid intensifying regulatory scrutiny.

Shein and Temu have expanded rapidly in international markets with low-cost clothing, accessories, and gadgets. But the removal of a U.S. customs exemption on low-value e-commerce parcels last year—with the European Union set to follow in July—could weigh on growth.