The online retailer Shein has been accused of breaching its own legal settlements and continuing to sell copycat items despite pledging to stop, with one of the world’s largest fashion groups accusing the company of being “repeat counterfeiters”.

Shein has long faced criticism that its blistering growth relied on cheap knock-offs of other people’s designs. The total number of copyright cases against the group has grown to nearly 100, according to legal filings.

The retailer has repeatedly denied the accusations, and said it invests heavily in systems to detect copyright infringements in its supply chain. But the persistence of the allegations and claims of repeat transgressions highlight a risk for potential investors as Shein attempts to pull off one of the largest — and most controversial — US initial public offerings in years.