Investors are turning away from the North Sea due to a lack of significant new reserves, according to the founder of a leading oil and gas exploration company.
Sir Bill Gammell, who founded Edinburgh-based Cairn Energy, said the balance of potential rewards and risks for investors in the North Sea was "not attractive".
Sir Bill, who is to stand down as chairman of the company after 25 years on the board, said he did not believe the North Sea was "disappearing" but argued a decline was evident in recent falls in production.
In an interview with The Times, he said: "If you think that North Sea production was down 35% in the last three years, with only 15 exploration wells drilled in the last year, in terms of new exploration it's not an area that people are putting much money into, because you're not likely to find significant new reserves.
"The fiscal policy is hugely important wherever you are, but there's been so many wells drilled in the North Sea, the chances are nothing major has been missed.
"Is the North Sea somewhere where the company is going to spend lots of new exploration dollars? No, because the risk reward is not attractive."
The former Scotland international rugby player told the newspaper: "I don't subscribe to the view that the North Sea is disappearing but I do think that a 35% decline over three years is telling us something."
Sir Bill declined to follow the heads of major oil companies Shell and BP in criticising an independent Scotland, telling the newspaper: "What happens post-independence in the North Sea is an argument for the future. But it is not affecting our decisions today."
His comments come just weeks after a report by industry body Oil & Gas UK said the search for new oil in UK waters is facing its biggest challenge in 50 years.
Only 15 exploration wells were drilled in 2013, continuing a steep downward trend since 2008 when 44 were drilled, it said.
Oil & Gas UK said that meant the last three years had seen the lowest rate of exploration activity in the history of the UK Continental Shelf (UKCS).
The report followed a UK Government-commissioned review that said investment in North Sea oil and gas will fall away sharply unless urgent action is taken to address serious underlying problems in the sector.
Former oil industry boss Sir Ian Wood warned there could be a 50% cut in investment over the second half of the decade unless further new commercial fields are discovered.
A Scottish Government spokeswoman said: "We welcome Sir Bill Gammell's comments on independence and how the North Sea has potential.
"As major oil expert Professor Alex Kemp acknowledges, there is plenty of life left off Scotland's shores.
"The BP Clair Ridge development will be in production until at least 2055 and we know that operators have just under £100 billion of capital investment within their current business plans.
"But to realise the North Sea's full potential then we need long-term predictability and stability for the industry, something that the UK Government has failed to achieve over the years.
"Sir Ian Wood's recent report into the future of the North Sea has confirmed that fiscal instability has been a significant factor in basin underperformance.
"In contrast to the approach taken by the UK, the Scottish Government is clear on the need for closer co-ordination and co-operation between the industry and relevant bodies. That is why we have called for the new regulator for the North Sea recommended in Sir Ian's report to be based in Aberdeen, and why we have proposed that the new energy department to be formed in an independent Scotland should be co-headquartered between Aberdeen and Glasgow."