BP boss Bob Dudley said he backed the estimates of leading oil tycoon Sir Ian Wood, who last month said Scottish Government figures are up to 60 per cent too high.

Sir Ian, founder of Wood Group, today reiterated his plea for a rethink, warning that relying on “unproven reserves” from shale gas was a “huge gamble and the stakes are too high”.

Dudley said in a statement on BP’s website that North Sea reserves are now largely “maturing”, adding: “I believe Sir Ian Wood correctly assesses its future potential. The opportunities today are smaller and more challenging to develop than in the past.”

Dudley said future investment on projects like offshore fracking and maintaining existing drills required “stability and certainty”, hinting that a decision to leave the UK would not be compatible with this.

“Our business invests for decades into the future,” he said. “It is important our plans are based on a realistic view of the North Sea’s future potential and the challenges the industry faces in continuing to operate here.

“As a major investor in Scotland – now and into the future – BP believes that the future prospects for the North Sea are best served by maintaining the existing capacity and integrity of the United Kingdom.”

Shell’s chief executive Ben van Beurden has already come out against Scottish Independence and today he too backed Sir Ian’s estimates.