The pro-independence campaign has mocked the Treasury's projection that Scots would be £1 worse off a year rather than £500 richer under independence.

Blair Jenkins, the chief executive of Yes Scotland, launched a "Pay a pound for Scotland" mock campaign yesterday, following The Herald's exclusive report of the Coalition Government's latest calculations.

The calculation by Chief Secretary to the Treasury Danny Alexander was intended to expose as a "myth" the SNP claim that people would be better off based on a single good year for the oil industry.

But yesterday Mr Jenkins countered: "If the cost of creating a more equal and fairer Scotland was only £1, I'm certain most Scots would think that a price worth paying.

"It is remarkable that at this early stage in the campaign, the Treasury has conceded that people in Scotland would be financially no worse off under independence."

Mr Jenkins said independence would allow Scotland to choose a different path to Westminster, such as by scrapping the £250 million a year spent on nuclear weapons.

Mr Alexander told The Herald: "Basing a case for Scotland to be independent forever on one good year of oil revenues is incredibly misleading."

First Minister Alex Salmond pointed out last week that oil with a wholesale value of £1.5 trillion remains untapped.

A social attitudes survey conducted just over a year ago suggested a majority of voters would back independence in 2014 if they believed their standard of living would remain about the same, but the gain or loss of £500 annually could sway the result either way.

Meanwhile, Better Together leader Alistair Darling will today begin a tour of Scotland to spread the pro-Union message.

He said: "Over the next few months, I want to get to every part of Scotland and I want to hear as many views as possible."