Oil industry leaders have warned that a new windfall tax could put billions of pounds of investment at risk over the next decade.
Oil & Gas UK said the tax could cost the North Sea industry £50billion over the next 10 years.
Chancellor George Osborne said oil companies would face £2billion of new taxes on their windfall profits, but Oil & Gas UK warned that the move could jeopardise tens of thousands of jobs.
A string of firms, including the Norwegian giant Statoil and Valiant Petroleum, have cancelled or delayed plans for North Sea exploration following the Chancellor's announcement in last month's Budget.
Mike Tholen, Oil & Gas UK's economic director, said: "It is undoubtedly the case that investors will be reappraising investment opportunities in light of the tax increase announced in the Budget."
A spokesman for the group said up to £40billion worth of investment had been identified over the next five years.
Labour's Aberdeen Central candidate Lewis Macdonald said the warning was "a profoundly concerning development", adding: "This tax has been hugely ill-thought out and introduced without proper consideration.
"We cannot afford to see jobs being put at risk for a policy that will at best reduce petrol prices by a fraction of what Labour's plans to scrap the VAT increase would have."
SNP leader Alex Salmond blamed successive Westminster governments for the "incompetent and shabby fashion" in which they had treated Scotland's oil wealth.
He said: "The Tory Chancellor's ill-thought through tax changes run the risk of diverting vital investment away from the North Sea, threatening jobs, and only now are we discovering that this could run into tens of billions of pounds."