A group of 70 charities, NGOs and trade unions is calling on the government to ensure that the repeal bill does not result in a "power grab" by ministers and a sidelining of the devolved nations in the Brexit process.
Members of the alliance, which is coordinated by the campaign group Unlock Democracy and funded by grant-makers including the Barrow Cadbury Trust, the Paul Hamlyn Foundation and the Lloyds Bank Foundation for England and Wales, include the National Council for Voluntary Organisations, Friends of the Earth, Amnesty International and Greenpeace.
The group is calling for clear limits to and safeguards on the powers that would be given to ministers in the bill and "robust parliamentary scrutiny at all levels with appropriate levels of transparency and debate" around the process of the UK leaving the EU.
MPs will debate the European Union (Withdrawal) Bill, commonly known as the repeal bill, when its second reading starts on 7 September.
"In the bill the government proposes to confer significant powers to ministers to transpose EU [law] onto the UK statute book using secondary legislation," said a statement from the alliance today.
"This legislation, commonly in the form of statutory instruments, is little understood, poorly scrutinised by parliament and consequently not democratically accountable.
"Although these delegated powers are meant to make technical changes to legislation, in recent years ministers have used them to make highly controversial and sweeping policy changes, including: changing regulations to allow fracking; abolishing maintenance grants for students; and adding the recent and controversial so-called ‘rape clause’ to tax credits."
The alliance, which said it took no position on the outcome of the EU referendum, said it would be engaging with MPs from all parties over the coming months to ensure the best possible outcome for the repeal bill.
Samuel Lowe, campaign lead (Brexit and trade policy) at Friends of the Earth, said: "About 80 per cent of our environmental protections come from the EU and we need them brought over into UK law so that they work just like they do now.
"This isn’t ‘red tape’ – they are rules that exist for a reason: to protect our beaches, air and wildlife, and nobody wants to see these threatened so we can’t let anything fall between the gaps."