Some British firms could be complicit in the use of forced labour in China's Xinjiang region, an MPs' report says.
The Business, Energy and Industrial Strategy Committee said there was a lack of transparency in firms' supply chains and failures in government.
Xinjiang, in north-west China, is home to the Uighur Muslim population.
China has been accused of committing genocide and crimes against humanity through its repression of the Uighurs - allegations it denies.
MPs said UK firms in fashion, retail, media and technology could all be implicated in the use of forced labour, and it was time to fine and blacklist those that failed to change.
The BEIS committee said it was appalled companies still cannot guarantee that their supply chains are free from forced labour. Those that cannot prove they don't have links with Xinjiang should face sanctions, the MPs said.
The report recommends the government accelerates proposals to amend and strengthen the Modern Slavery Act 2015.
It also recommends the government develops a policy framework for creating a whitelist and blacklist of companies which do and do not meet their obligations to uphold human rights throughout their supply chains.
The findings come as some senior Conservative MPs attacked Boris Johnson for failing to adopt a tougher stance on Beijing in his integrated review of security, defence, development and foreign policy published on Tuesday.
For the inquiry, the BEIS committee heard from a variety of companies including Boohoo, H&M, TikTok, The North Face and Nike.
The report found it "clearly unacceptable" that fashion retailer Boohoo had only minimal data about the different tiers in its supply chain.
A Boohoo spokeswoman said the company "has made extensive improvements to its supply chain practices", and that the "group looks forward to publishing the details of its UK supply chain next week".
While the report had widespread concerns about retailers and suppliers using cotton from Xinjiang, other companies were also in the committee's sights.
MPs were particularly critical of Disney which, they said, had refused to appear before it to give oral evidence on the making of the film Mulan - parts of which were shot in China's Xinjiang province.
"The Walt Disney Company has a responsibility to demonstrate that none of their actions supported oppression or undermined human rights during the production of Mulan," it said.
"The Walt Disney Company still has many questions to answer, particularly in relation to concerns about whether it completed adequate risk assessments and put in place sufficient safeguarding measures during the production of Mulan in Xinjiang, and why it refused to answer questions before our committee."
A Disney spokeswoman responded: "We respect the role and views of the select committee and when approached by the committee we provided relevant background and robust written testimony to them."
Nusrat Ghani, Conservative MP and lead BEIS Committee member looking at forced labour in UK, said: "It is deeply concerning that companies selling to millions of British customers cannot guarantee that their supply chains are free from forced labour.
"Modern slavery legislation and BEIS Department policy are not fit for purpose in tackling this grave situation. Amid compelling evidence of abuses, there has been a sorry absence of significant new Government measures to prohibit UK businesses from profiting from the forced labour of Uighurs in Xinjiang and other parts of China."
But a government spokesperson said: "Forced labour is one of the world's most despicable practices and the government will not stand for it, whether this exploitation takes place in the UK or abroad.
"The UK is the first country in the world to require businesses to report on how they are tackling modern slavery and forced labour in their operations and supply chains, and we are taking forward plans to extend that to certain public bodies and introduce financial penalties for organisations that don't comply."
As evidence of Uighur Muslims being abused and compelled to work in fields and factories in Xinjiang has mounted, so too has unease about the hidden cost of some clothes.
A fifth of the world's cotton comes from the region, and a lack of transparency in supply chains may mean some British firms are unwittingly complicit in the abuse.
The government says financial penalties will be introduced for firms found to be breaching an updated version of the Modern Slavery Act - but has yet to reveal full details or a timescale.
The industry too is keen to be seen to be acting. The Better Cotton Initiative, which focuses on sustainable production and supplies some big high street names, has ceased sourcing from Xinjiang.
Retailers know any reputational stain may be hard for customers to wear. But with so many steps in the production process, it isn't always easy to know the provenance of the shirt on your back.