Senior directors at online fashion giant Boohoo knew about "serious issues" with how workers at its supply chain were treated months before the scandal broke, a review has found.
Lawyers for the company found that staff at a site in Leicester worked in poor conditions on low pay - but that no crimes had been committed.
Alison Levitt QC, the lawyer who undertook the review of Boohoo's practices, said senior directors knew "for a fact" that there were "very serious issues" at the factory in Leicester from at least December last year.
She said that while a programme had been put in place to "remedy" the issues, the company "did not move quickly enough".
Questions over Boohoo's treatment of workers in its supply train had previously been raised in the media and in Parliament.
Issues had been highlighted as early as 2017 by a Channel 4 Dispatches documentary into Britain's cheap clothing market.
In May 2018 the Financial Times published a story about "labour exploitation in Britain's garment industry" questioning how Boohoo was able to sell such cheap clothes, while months later, in November, MPs grilled then co-chief executive Carol Kane about Boohoo's pricing.
Ms Levitt was appointed to conduct the review after the concerns resurfaced amid Leicester's local lockdown.
In July this year, the Sunday Times published claims about factory conditions in the city.
The BBC and the Guardian had also both reported on problems in Leicester previously.
Ms Levitt's review said Boohoo "capitalised on the commercial opportunities offered by lockdown and believed that it was supporting Leicester factories by not cancelling orders, but took no responsibility for the consequences for those who made the clothes they sold".
She added: "Inaction by the authorities has contributed significantly to the deficiencies ... If the law is not enforced, this sends a clear message that the violations are not important and the people affected do not matter."
The fashion company has said it will implement "necessary enhancements" following the review and that issues "will not reoccur".
Boohoo chief executive John Lyttle said: "Ms Levitt's Independent Review ... has identified significant and clearly unacceptable issues in our supply chain, and the steps we had taken to address them, but it is clear that we need to go further and faster to improve our governance, oversight and compliance.
"As a result, the Group is implementing necessary enhancements to its supplier audit and compliance procedures, and the board's oversight of these matters will increase significantly.
"As a board, we recognise that we need to rebuild confidence that these matters will be dealt with appropriately and sensitively, and that they will not recur."