THE SNP should stop "bleating" about alleged Westminster vetoes in the new Scotland Bill and offer some concrete alternatives, the Scottish Secretary's legal adviser said yesterday.

Professor Adam Tomkins, who was last week made an unpaid adviser to David Mundell on devolution, said that instead of going into "attack mode", the Scottish Government should put forward its own detailed amendments in keeping with the Smith Commission - if it could.

The angry intervention comes amid a row over eight welfare, energy and electoral clauses in the Bill, which was published by the Tory government on Thursday.

Because these refer to Scottish Ministers requiring the "agreement" of the Scottish Secretary to exercise new powers, the SNP say they are unacceptable "vetoes".

Nicola Sturgeon highlighted such a clause on Universal Credit at First Minister's Questions.

"If this parliament wants to abolish the bedroom tax... the UK government would still have a right of veto over whether we could or not. I'm sorry, but that is not devolution." she said.

However Tomkins said the Bill was unlike previous devolution, in which there was a clear split between reserved and devolved powers, as it would create "a new category of shared powers", so it was natural for both Edinburgh and London to have a say.

In the case of Universal Credit, the benefit stayed reserved to Westminster, but Holyrood had "limited" powers to alter the housing element and its administration.

He said: "The language in the legislation that the Scottish Government is objecting to is language which is designed to allow for this kind of inter-governmental cooperation, which will be required in order to deliver successfully what Smith agreed.

"If there's a disagreement then there's a neutral arbiter in the form of the courts. It's absolutely not a veto, because the Secretary of State is going to be subject to judicial oversight."

Seven clauses in the Bill also say London needs Edinburgh's agreement to act.

The Bill is meant to put last year's Smith Commission on devolution into effect, and so deliver the pre-referendum "vow" of more powers for Holyrood.

It will give MSPs control of income tax rates and thresholds, a share of VAT, new welfare powers worth £2.5bn, and a power to "top up" benefits.

When draft welfare clauses were published in January, Tomkins publicly criticised them for falling short.

However he said those in the Bill were "very substantially different".

He said: "What would have been nice would have been an acknowledgement by the Scottish Government rather than immediately going on attack mode about these alleged vetoes.

"If the Scottish Government have a better way of expressing, in legislation, what Smith agreed on the way these powers should be shared, then rather than bleating about vetoes they should produce their alternative text and we can then have a look at it."

He added it was "inevitable" the Bill would be changed as it passed through parliament, particularly as welfare devolution was "breaking new ground" in Whitehall.

The John Millar Professor of Public Law at the University of Glasgow, Tomkins was a prominent No campaigner and a Tory representative on the Smith Commission.

SNP Westminster leader Angus Robertson said: "It is not too late for David Cameron and the Tories to do the right thing and admit the Scotland Bill must be strengthened.

"We want to see powers over business taxes, employment law, the minimum wage and welfare.. to enable us to strengthen and grow the Scottish economy while supporting and empowering the most vulnerable people.

"Amendments tabled to the Scotland Bill by SNP MPs will reflect these aims."