A spokesperson for Shein and a spokesperson for Britain's markets watchdog, the Financial Conduct Authority (FCA), declined to comment. Both the sources, who have knowledge of the deal, declined to be named as they were not authorised to speak to the media.

The ultra-fast fashion company, facing major headwinds to a U.S. public stock listing, filed a confidential registration with the London Stock Exchange's markets regulator early in June.

Shein became one of the biggest fashion retailers in the world during the pandemic, but has faced criticism over the environmental impact of its business model. The firm has also come under fire for some of its working practices,