Shein, whose clothes have been advertised by celebrities including Georgia Toffolo, has been criticised by human rights campaigners and fashion industry chiefs.
Shein will reportedly push its blockbuster London listing back into the second half of this year after Donald Trump's tax clampdown on parcels.
Currently, retailers, including Shein, avoid US tariffs on parcels worth $800 (£645) or less.
Fast fashion: Shein's clothes have been advertised by celebrities including Georgia Toffolo (pictured).
The Government is facing pressure to axe a similar loophole, which allows parcels to be shipped directly to consumers with zero duty if the value of the parcels is less than £135.
