John Swinney has "nowhere to hide" now that the Scottish Government is being given more tax and welfare powers, David Mundell, the Scottish Secretary, has warned.

The Conservative Cabinet minister said that the Scottish Finance Secretary was facing a "reality check" and from now on would have to justify the tax choices he made to Scottish voters.

Speaking after Mr Swinney unveiled his latest Budget, for 2016/17, in which he emulated Chancellor George Osborne by keeping the Scottish rate of income tax the same as the UK's, Mr Mundell said in an exclusive interview with The Herald: "It's a reality check because once you have these responsibilities, there is nowhere to hide."

Air passenger duty was a good example of the new reality facing Nicola Sturgeon and her colleagues, said the Secretary of State.

"In the past, the SNP position was that they would abolish APD and it would be wonderful in Scotland because you wouldn't pay it. Now, they're undergoing a consultation on implementing it because, when you're responsible for these things, you just can't write off £250 million with some glib soundbite because where is that money going to come from?

"That's the change," declared Mr Mundell. "They know that raising tax is not a popular thing to do when it's a reality.

"Lots of people are prepared to say: 'I would pay a bit more tax for this and that' to opinion pollsters but election results over a long period of that when it comes to making a decision as to whether you would actually pay it, people are a lot more reticent to pay extra tax."

Mr Mundell said he understood the rationale for certain aspects of Mr Swinney's Budget, coming as it did just months before the Holyrood election, but stressed: "What I don't accept is the Budget that was delivered was in any way forced upon him by the UK Government or anyone else.

"It was a series of conscious choices; one, to put an additional burden on local government, and, two, not to remove the freebies voters enjoy. It was certainly done with the election in mind."

The Scottish Secretary said he now wanted the fiscal framework, the mechanism to introduce the new tax powers, agreed as quickly as possible.

While he stressed he was confident an agreement could be reached by the Valentine's Day deadline set by the First Minister and Prime Minister David Cameron, Mr Mundell pointed out it was a negotiation between two governments, so nothing could be guaranteed.

But he warned the SNP Government not to use the framework talks to gain political advantage, saying: "People would find it incomprehensible if the opportunity for the Scottish Government, particularly one run by the SNP, to take steps, that would see major game-changing powers, was not applied to the Scottish Parliament."