ANY UK constitution which does not establish a route out of the Union will be "fundamentally flawed", Andy Burnham has been warned.
Last week, the new Labour leader suggested that there was an increased need for the UK to have a “written constitution” following plans for extended devolution in England.
The Prime Minister suggested that the case for the constitution – the set of rules and standards outlining how the country is governed – to be written into a single overarching document, as is the case in countries such as Spain and the US, was growing stronger.
As it stands, the UK’s constitution is uncodified, existing across a series of sources including statute law, common law, and unwritten conventions.
The National revealed how pro-independence parties in Scotland and Wales demanded that any written UK constitution must spell out the route for a constituent to leave the Union.
Burnham's comments on the constitution come after he held a meeting with First Minister John Swinney in Glasgow last week, in which he warned that further talks on an independence referendum are "off limits".
Now, the SNP have once again urged Burnham to include in any constitution how UK nations can leave the Union, saying any document would be “fundamentally flawed” without such a clause.
SNP Westminster leader Dave Doogan said: “Andy Burnham spent the weekend talking about a written UK constitution after telling Scotland discussion about our constitutional future is ‘off limits’.
“There are pro-independence first ministers in Scotland, Wales and Northern Ireland – that’s the context of this discussion, so clearly a written UK constitution is fundamentally flawed if it doesn’t spell out a path to leaving it.
“The Scottish Parliament has voted for the Scottish people’s right to decide, there are a record number of pro-independence MSPs in Holyrood and opinion polling consistently shows independence is the preferred position of the Scottish people.
“Westminster cannot continue to ignore that reality.
“Andy Burnham is right to say Westminster has hoarded too much power and he is right to raise the question of where power lies in these islands, but he will never address the answer to that question by denying democracy to the Scottish people.”
The UK Government has been contacted for comment.