ALEX Salmond has upped the referendum rhetoric by branding Westminster politicians "thieves" for allegedly squandering the nation's oil and gas reserves over many years as the North Sea became the latest independence battleground between London and Edinburgh.

The First Minister's outburst earned him a stern rebuke from Baroness Goldie, the former Scottish Conservative leader, who said such language "ill becomes a first minister" and insisted "playground yah-boo politics have no role to play" in the debate.

But the day was marked by two competing visions for the future of the multi-billion oil and gas industry.

Steven Camley's cartoon

David Cameron insisted only the UK Government with its economic "broad shoulders" could keep it afloat into the future, while Mr Salmond claimed the 'biggest is best' argument did not hold water and pointed to Norway, which had accumulated a £450 billion oil fund after having managed its resources far better than successive UK governments.

On an extraordinary day for the referendum campaign, not one but two Cabinets met just miles apart. In Shell's Aberdeen HQ, the Prime Minister and his Coalition colleagues held their first such meeting in Scotland while down the road in the more modest surroundings of a church hall in Portlethen the First Minister and his colleagues gathered.

The two sides met as retired oil executive Sir Ian Wood published a report, commissioned by Whitehall, which called for measures to generate £200bn for the British economy by ensuring up to 4bn extra barrels of oil were recovered from the North Sea over the next 20 years.

Both governments swiftly backed Sir Ian's recommendations for better business collaboration to help maximise oil and gas revenues and for establishing a Scottish-based regulator. There was also agreement over the Coalition's decision to locate a multi-million pound carbon capture and storage site at Peterhead.

Earlier, Mr Cameron visited an oil rig, 150 miles off the Aberdeenshire coast, and insisted the industry was better supported by the UK as a "top 10 economy" than it would be by an independent Scotland. Downing Street pointed out how tax revenues from oil and gas in 2012/13 were £4.7bn lower than the previous year; a drop of more than 40% and a sum equivalent to two-thirds of Scotland's education budget.

Mr Cameron said: "It's more important than ever that the North Sea oil and gas industry has the backing of the whole of the United Kingdom; it has the deep pockets and the broad shoulders of the UK economy to make sure there are the tax allowances, the solidity, the investment, to make sure we can go on benefiting from this for many years to come."

Describing the oil and gas sector as an international success story that had benefited both Scotland and the UK as a whole, the PM added: "As we get to the later stages of the North Sea, long-term investment, deep pockets from the UK Government is going to be really important to recover that oil and gas."

But Mr Salmond, who decried Mr Cameron for simply "jetting into Scotland and jetting out again", insisted an independent Scotland would cope perfectly well in developing the remaining oil and gas resources and attacked Tory governments for squandering Scottish resources over the years.

Stressing how there was still more to come in value terms from North Sea oil and gas, the FM addressed the Prime Minister's warning, saying: "We've heard all of this from Tories before because they told us 30 years ago it was not worth anything... We're hearing the same old song from a discredited Conservative government."

Mr Salmond noted how he had "got some form in oil and gas as I was an energy economist before I fell among thieves, by which I mean the House of Commons and not the Scottish Parliament or the Scottish Government".

The SNP administration has put forward plans to establish two separate oil funds if there is a Yes vote: one short-term to help deal with fluctuations in oil and gas revenues, the other a long-term savings fund.

Mr Salmond argued that far from creating instability, independence would give the industry a more secure future.

"We've had 16 tax changes in the North Sea in 10 years, we've had 14 oil ministers in the last 17 years, three in the last four years, one thing that Scottish control of oil and gas resources will offer is a much more stable, long-term policy," he added.