David Cameron will today claim that only the UK government has the financial muscle to help extract an extra 4 billion barrels of oil from the North Sea which would be worth up to £200 billion.
Revenues from the North Sea account for 2% of the UK economy but 20% of the GDP of an independent Scotland - which Number 10 claims would be exposed to the volatility of oil prices and less able to extract the remaining oil which is both harder to reach and more expensive to extract.
Mr Cameron will also claim that Scotland would be less able to absorb the huge costs of decommissioning the old oil fields and platforms.
Figures show North Sea revenues brought in more than £11.25 billion for the Treasury in 2011-12 but £4.7 billion less the following year.
Projections suggest the revenues will continue to fall in the next four years.
By contrast, the SNP claims 94% of the oil and gas platforms are in Scottish waters so the industry helps make the economic case for an independent Scotland.
First Minister Alex Salmond claims he'd put some of the revenues into an oil find (like Norway has done since the 1970s) to maximise the future revenue for an independent Scotland.
Both the UK and Scottish cabinets will meet in Aberdeenshire today just a few miles apart as the battle over independence moves to Scotland's north-east coast.