NICOLA Sturgeon’s Government has been warned by Whitehall to “stop dragging its feet” on implementing its new welfare plans, throwing up the prospect that UK ministers might have to step in to maintain payments.

Last month, MSPs formally backed the transfer of 11 new benefits from Westminster to Holyrood, including Personal Independence Payments and the Carer's Allowance. They amount to some £3 billion a year and are relied upon annually by 1.4 million Scots.

Jeane Freeman, the SNP Government’s Social Security Minister, hailed the occasion as “historic,” saying it marked the "single biggest transfer of powers since devolution began".

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But today David Mundell, the Scottish Secretary, and his Cabinet colleague Esther McVey, the Work and Pensions Secretary, warn the First Minister that her administration is running the risk of missing a key deadline, April 2020, to introduce her plans, including establishing a new social security agency.

Already, Whitehall has angered Scottish ministers by suggesting that it is ready to step in should the SNP Government find it impossible to meet the deadline.

In a joint article for The Herald, the UK Cabinet ministers say: “What really matters is delivering the smooth transfer of welfare powers by the agreed date of April 2020 while ensuring payments are not put at risk. This is our priority and it has to be the Scottish Government’s also.

“Key to this is the Scottish Government establishing the first Scottish social security agency.

“Worryingly, they haven’t yet set out a timetable for the agency being fully operational and capable of delivering the benefits it will administer. They need to stop dragging their feet or there is a real risk they will miss the deadline.”

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The Secretaries of State explain the UK Government has already introduced Universal Credit choices for the Scottish Government, has supported the implementation of Fair Start Scotland, and has been helping the SNP administration bring in a Carer’s Allowance supplement.

“But we cannot properly support the Scottish Government in managing the transfer of the remaining devolved powers, including the key disability benefits, until they produce plans,” insist Mr Mundell and Ms McVey.

“Time is ticking and the ball is in the Scottish Government’s court,” they declare.

The UK ministers argue that too often in Scotland sensitive welfare issues are “turned into political footballs” and “weaponised”.

This, they insist, “needs to end and we believe the greater responsibility that comes with more powers will improve the debate about welfare in Scotland”.

Mr Mundell and Ms McVey add: “Scottish Government ministers are entitled to question the UK benefits system and we expect they will. But the questions now for them are simple. What are their plans and where is their timetable?”

Last month when she appeared before a Holyrood committee the Work and Pensions Secretary suggested Whitehall would have to “put measures in place to ensure that, if the Scottish Government can’t do it, we will no doubt end up continuing to do it through agency agreements”.

But Ms Freeman responding to the joint article said: “We are disappointed that the UK Government has chosen this route to raise issues which are, frankly, inaccurate.

“Our plans to establish Social Security Scotland are on track and we will ensure Scotland has a social security system which has dignity and respect at its heart.”

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The Scottish minister pointed out the SNP Government had already established an interim headquarters in Dundee and was recruiting to the agency, which, when fully operational, would deliver devolved benefits to 1.4m people a year.

“Critical to all of this is the DWP’s capacity to meet the priority both Secretaries of State have assured us they have placed on co-operative work with us.

“We have experienced two DWP-initiated delays to our plans recently but we will continue to work co-operatively with the UK Government to ensure that their work and ours are complementary and productive,” added Ms Freeman.