SCOTS should not believe the three main parties' promises of devolved tax powers and should vote for independence unless they want to end up with a "paltry", "watered down" offer like the Welsh, Parliament has heard.

Plaid Cymru's economic spokesman Jonathan Edwards insisted the Scottish should dismiss the three main pro-Union parties' promise of more devolved powers, including over tax-setting, as "jam tomorrow" that will be reneged on if Scotland votes No.

Mr Edwards said that had happened to the Welsh as the recommendations of the cross-party consensual Silk Commission for devolved powers for the principality had been "cherry picked" and "watered down" by the coalition Government putting together the Wales Bill.

Putting forward amendments that would give the Welsh government more power over infrastructure spending and borrowing, Mr Edwards said it was clear the UK is moving to a "far looser union".

During the Bill's report stage, he said: "Now all the unionist parties are falling over themselves to offer increased devolution in Scotland despite having previously said that increased devolution should not be an option in the referendum.

"How they must be kicking themselves now not to have that third option on the ballot paper.

"Who will believe a word they say when they promise their jam tomorrow?

"I would say, based on past evidence, and we've had an inkling of it today by the Treasury Minister (David Gauke), that the only way for the people of Scotland to guarantee more powers for Scotland is to vote for independence.

"I will draw the people of Scotland's attention to the Wales Bill - here we have a Government that set up a cross-party commission to bring forward a consensus, which carefully put together a fully endorsed package of reforms.

"The Conservatives and the Liberal Democrats then reneged on their word by cherry picking and watering down the recommendations of a cross-party commission.

"They then added restrictions and caveats to further render the powers unusable through mechanisms such as the lock-step.

"The UK Government's attempts to strangle the cross-party Silk Commission's original recommendations by adding caveats, restrictions and lock-steps should be a salutary reminder to the Scottish people of the sincerity of Westminster's promises regarding further devolution.

"If the Wales Bill is anything to go by, essentially what the Government here does is make a big headline-grabbing announcement of promising more devolution, only to reveal a paltry offer when the surface is scratched away."