The UK Government has published a list of the devolved powers at the centre of a Brexit dispute with Scottish and Welsh ministers.
The Scottish and Welsh governments want all powers returning from Brussels to come under their control.
However, ministers at Westminster want to retain temporary control over 24 areas, including fishing and farming. with the aim of incorporating new legislation into UK-wide frameworks.
The UK Government now plans to push ahead with a draft amendment to the EU Withdrawal Bill while negotiations continue with devolved nations.
UK Cabinet Office Minister David Lidington said publishing the document gave “cast iron evidence” more powers would be given to Scottish, Welsh and Northern Irish administrations.
“The vast majority of these new powers will be in the control of the devolved administrations on the day we leave the EU,” he said. “There is a much smaller group of powers where the devolved governments will be required to follow current EU laws for a little bit longer while we work out a new UK approach.”
Mr Lidington said he had “moved a considerable distance” but needed to “protect the UK internal market”.
However, the position was dismissed as confirmation of “a major power grab” by Scottish Brexit Minister Michael Russell, who highlighted how “the threat is most immediate” to agriculture, GM crops, fishing, the environment and food standards.
He said: “Unless the bill is changed Westminster could soon be in control of these policies amounting to a major power grab and a rewriting of the devolution settlement the people of Scotland voted for so decisively.
“We are not opposed to working together on joint frameworks in some of these areas but we have been given no assurances on how frameworks will operate, who makes the decisions about them and how we would be able to ensure Scotland’s interests are properly protected.”
National Farmers Union Scotland president Andrew McCornick called for all decisions surrounding Scottish agricultural policy to be made in Scotland and demanded an end to delays to allow farmers and crofters to take decisions ready for next year.
“For the Scottish farming and food sectors, many of our key priorities lie within those 24 policy areas identified as needing further detailed discussions,” he said.
“Decisions on Scotland’s allocation of agricultural funding, and absolute recognition that Scotland can decide on agricultural policy priorities to suit our unique farming and crofting landscape, must be agreed to allow us to move on.”