A senior MP has raised 'profound concerns' with City regulators about a lack of transparency from Shein ahead of the Chinese fast fashion giant's possible £50billion listing on the London stock market.

Liam Byrne, chairman of the business select committee, wrote to the Financial Conduct Authority (FCA) and London Stock Exchange to ask how they will scrutinise the firm as it plans one of Britain's biggest ever flotations.

Shein is waiting for approval for its £50billion London listing but campaigners have complained about allegations of abuse in its supply chain.

MPs were left fuming this week after the fast fashion giant's top UK lawyer refused to say whether its cheap clothes are linked to slave labour in China's Xinjiang region.

In a letter to Dame Julia Hoggett, chief executive of the London bourse, Byrne said his committee were 'profoundly concerned at the lack of candid and open answers to some extremely simple, basic questions about the integrity of Shein's supply chain'.

He asked Hoggett to respond with 'what checks, if any, the London Stock Exchange has in place to authenticate statements by firms seeking to list, with particular regard to their safeguards against the use of forced labour in their products'.

Byrne has also asked FCA boss Nikhil Rathi to set out the checks the watchdog carries out to 'ensure all legal risks are disclosed'. There have been worries that Shein is not being fully transparent with regulators about its supply chain. Chancellor Rachel Reeves is in China for talks on economic and financial cooperation, which could help Shein win regulatory approvals.

Also on the trip is Rathi and David Schwimmer, boss of the London Stock Exchange Group that owns the LSE.

At this week's hearing with MPs, Shein lawyer Yinan Zhu was accused of being 'disrespectful' and 'ridiculous' after she declined to comment on whether the company believes there is slavery happening in the region.

Chinese authorities deny claims they have set up labour camps for Uyghurs – the largest ethnic minority group in Xinjiang – and other Muslim minority groups. Campaigners have said they are concerned Shein's suppliers are likely to be using materials made in such camps. Shein insists it has a 'zero tolerance' approach to forced labour.