Jeremy Corbyn has rebuffed the Scottish Labour leader’s call for a “new Act of Union”.
Kezia Dugdale proposed a federal structure for the UK last month in a bid to end the constitutional wrangling across the country and stave off the threat of independence.
The UK Labour leader took issue with the MSP’s choice of words in an interview with the BBC.
Mr Corbyn agreed with Ms Dugdale in saying there needs to be a convention to investigate alternative constitutional arrangements.
But he added: “I would not use the words new Act of Union.”
The Islington North MP also said there is no need for a second independence referendum and questioned whether the devolution of immigration powers to Holyrood is possible.
Mr Corbyn said: “There is a huge issue about regional government across England, and there is a need to have a discussion about the relative powers in Scotland, in Wales and in Northern Ireland of devolved assemblies.”
A spokesman for Scottish Labour said: “Kezia Dugdale has proposed a new Act of Union, to strengthen our union across the whole of the UK for generations to come.
“Being part of the UK protects jobs and the money we need to invest in our public services.”
Scottish Conservative leader Ruth Davidson said: “I never thought I’d find myself agreeing with Jeremy Corbyn.
“But he’s quite right to reject the idea of a new act of union; it’s clearly little more than a Scottish Labour gimmick, from a party all at sea on the constitution.
“Instead of constant flip-flopping on the issue, Labour should be standing full-square behind Scotland’s decision to stay part of the UK.
“That’s what the Scottish Conservatives are doing – fighting Nicola Sturgeon’s attempts to rerun the referendum and providing the sort of strong opposition to the SNP that our country needs.”