Scotland Bill: 'Scottish ministers can triple the dole - if they can find the money'

The changes would allow Scottish ministers to create new benefits in devolved areas and top up other welfare payments, as well as give Holyrood control over abortion.

There would also have to be a referendum before the Scottish Parliament could be scrapped.

But a senior UK Government source admitted that Scots may not have the "full picture” on the new powers by the time they become law.

London and Edinburgh are still wrangling over how to calculate the money involved, the so-called “fiscal framework”.

A source said: “We are keen to have the fiscal framework in place by the time the Scotland Bill clears its last parliamentary hurdle next spring, because without it we won’t have the full picture."

Former Labour Prime Minister Gordon Brown hailed the new amendments, saying that they would deliver the 'Vow' and allow Scotland to repeal the Tory's planned tax credit cuts.

But Deputy First Minister John Swinney said the changes fell short of implementing the cross-party Smith Commission agreement on further devolution.

More work was needed before the SNP could back the Bill, he warned, saying that the Scottish Government opposed what it saw as continued restrictions, including that UK ministers could still "effectively veto" some welfare changes.

Tory ministers have always rejected the idea of a veto, but they have changed the language in the BIll to include a presumption that Scottish minister's social security policies will be implemented.

However, UK ministers would still be able to postpone the changes, citing administrative difficulties.

Mr Swinney said: "Unfortunately the set of amendments the UK Government have promised today still fail to deliver Smith, and still fail Scotland.

“In areas such as social security, employment support and the Crown Estate, the Scotland Bill does not fully devolve new powers and restricts the ability of future Scottish Governments to exercise power without interference."

He added that the Bill must also be accompanied "by a revised funding settlement that is fair and workable".

Labour’s Ian Murray said many of the major amendments had first been put forward by his party.

He added: “The government have caved under pressure from Labour when they realised they were on the wrong side of the argument.”

He also accused the SNP of denouncing the changes to the BIll "before they had even seen them".

Other amendments will give Holyrood greater flexibility over creating new benefits for carers.

Mr Mundell said that "any reasonable person talking a reasonable view (would find that) the Bill met the Smith Commission (agreement)".

He said that he did not expect the SNP to be "dancing in the streets... because their position is that they want independence and whatever amendments I make ... it would never be enough".

He added that under the planned new powers: “If the Scottish Government wanted to treble jobseekers allowance they could.

“If they want to do that they can do it provided they have got the money.

"There just has to be mechanism, administrative arrangements to make sure people get the cheque.”

Overall, the Scotland Bill will transfer almost full control over income tax and responsibility for a £2.5 billion welfare budget to Holyrood.

It is the result of the cross-party Smith talks, set up in the wake of last year’s independence referendum result.

MPs will debate the proposed changes next Monday.

First Minister Nicola Sturgeon has warned that her party’s MSPs would only support the Scotland Bill if the accompanying deal on funding was fair.

Earlier this month former Treasury minister Danny Alexander said MPs should be able to consider the fiscal framework before the Bill becomes law.

The ex-Highland MP said: "In a way, the fiscal framework that lies behind the bill is at least as important as what is on the face of the bill."