Scottish and UK ministers will meet for further Brexit talks later with still no agreement on who should exercise powers which return from Brussels.
The Welsh and Scottish governments have accused the UK government of proposing a “power grab”.
A UK government source has told the BBC it may amend the EU Withdrawal Bill even without a deal with Edinburgh.
A letter obtained by the BBC suggests UK ministers want to publish details of which powers should apply UK-wide.
A UK government source indicated that even without a deal, it would press ahead with changes to the EU Withdrawal Bill, possibly next week.
The letter obtained by the BBC suggests that UK ministers have found it “difficult to counter” the “Westminster power grab” claims.
Key paragraphs from the letter
In order to rebut these suggestions, they now want to publish details of the “limited number of policy areas” where they believe frameworks should operate on a UK-wide basis.
The Scottish government agrees the proposals should be published – but believes they will show the extent of the powers Westminster wants to take control of.
Its Brexit secretary, Michael Russell, tweeted that the text of the leaked letter made it clear that “UK Ministers were discussing it last week and will push on no matter what Wales and Scotland says”.
He added: “So much for a partnership of equals”.
A further meeting of the joint ministerial committee involving the UK, Scottish and Welsh governments will take place on Thursday afternoon in London.
But there is little expectation of a breakthrough in the dispute being agreed.
What is the row all about?
The dispute centres on 111 areas such as agriculture and the environment which are devolved but are currently run in part by the European Union.
The controversial Clause 11 of the Brexit bill proposes that these powers initially return to Westminster while UK ministers decide which frameworks should operate on a UK-wide basis.
The UK government has since proposed changes that would mean about 85 of these powers going straight to Holyrood, while the remainder will become part of UK-wide frameworks.
But the Scottish government says these proposals are still not acceptable as they would effectively give the UK government a veto over some of Holyrood’s powers.
It has said it will withhold legislative consent for the EU Withdrawal Bill at Holyrood if an agreement is not reached, and has already introduced its own “continuity bill” at Holyrood.
Withholding consent would for the Withdrawal Bill would not amount to a veto of Brexit, would would make things very difficult politically for the prime minister.
The Scottish and Welsh governments are both pushing ahead with their own stop-gap Brexit legislation, in case agreement cannot be reached on the issues.
On Wednesday the Scottish government’s “continuity bill” passed its first vote at Holyrood by 94 votes to 30.
The bill would have the effect of bringing EU laws onto the domestic statute book ahead of Brexit.