“Both cases were resolved swiftly, with remediation steps including terminating contracts with underage employees, ensuring the payment of any outstanding wages, arranging medical checkups and facilitating repatriation to parents/legal guardians as needed,” Shein said.

“Following appropriate remediation, the contract manufacturers were permitted to resume business.”

Shein said it has now tightened its supplier policies. Under the new rules, any child labour or forced labour violations have become grounds for immediate termination of contracts.

The firm said the two cases were uncovered during the first nine months of 2023 and none were found in the last quarter of the year.

It comes as the company lays the groundwork for a potential sale of shares on the stock market.

The BBC understands that Shein filed initial documents for a London listing earlier this year.

In June, Marco Rubio, a leading Republican on the US Senate Intelligence Committee, and an ally of Donald Trump, wrote to then-UK Chancellor Jeremy Hunt warning him about “grave ethics concerns” and Shein’s “deep ties to the People’s Republic of China”.

“Slave labour, sweat shops, and trade tricks are the dirty secrets behind Shein’s success,” Mr Rubio wrote in his letter to Mr Hunt.

At the time, a spokesperson for the company said: “Shein has a zero-tolerance policy for forced labour and we are committed to respecting human rights. We take visibility across our entire supply chain seriously and we require our contract manufacturers to only source cotton from approved regions.”

That was just weeks after a report released by Swiss advocacy group Public Eye said excessive overtime was still common for many workers in Shein’s supply chain.

In response to the report, Shein told the BBC it was “working hard” to address the matters raised by Public Eye and had made “significant progress on enhancing conditions”.