A wider ranging alliance from the business, union, legal and environmental sectors has called on the government to ditch plans to remove a large number of EU-derived rules from the UK by the end of next year.
Such a move would "cause significant confusion and disruption" for businesses, workers, consumers and conservationists, it has said, according to the Financial Times.
The dozen or so organisations calling for the U-turn include the Institute of Directors, Trades Union Congress and Chartered Institute of Personnel and Development.
Roger Barker, director of policy and governance at the IoD, said: "Getting to grips with any resulting regulatory changes will impose a major new burden on business, which it could well do without".
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A bonfire of EU regulations is planned under the Retained EU Law Bill, potentially affecting up to 4,000 pieces of legislation, ranging from holiday pay, safe working hours and protection from discrimination, to the labelling of meat and eggs and the ban on the slaughter of seals.
It is backed by leading Eurosceptics and Brexiters, who believe the move will deliver a "productivity boost" to the UK economy.
But in a letter to business secretary Grant Shapps on Wednesday, the groups opposing the changes said scrapping EU laws would force businesses to deal with more uncertainty at an already difficult time of high inflation and energy bills.
Removing these laws could also put the UK "in breach" of the agreement struck with the EU by former prime minister Boris Johnson, the letter said, "bringing with it the prospect of additional tariffs hurting UK exporters and those who work for them".
The protest letter follows a separate intervention this week by CBI boss Tony Danker, who told ministers they should instead seek to improve the UK trade deal with the EU.
A government spokesperson said it was committed to taking full advantage of the benefits of Brexit, which was why it was pushing ahead with the Retained EU Law Bill.
They said: "This will allow us to ensure our laws and regulations best fit the needs of the country, including making sure we continue to protect and enhance workers' rights and support jobs."
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TUC general secretary Frances O'Grady said the bill had been "rushed through with no consultation and no real thought for the impacts on workers, businesses, consumers and the environment".
Greener UK, the Employment Lawyers Association, Civil Society Alliance, Wildlife and Countryside Link, Hope for Justice, Wales Council for Voluntary Action and Wales Civil Society Forum, have also signed the letter to the Government.
Other organisations, from consumer goods group Which? to the NFU and British Safety Council, have also called for the bill to be delayed or scrapped.
