OIL and gas worth more than £1 trillion has still to be extracted from the North Sea, First Minister Alex Salmond told a conference of experts.

But he said investment by the industry to get the oil out had to be backed by a stable tax regime and criticised Chancellor George Osborne's £2 billion oil tax increase in last year's Budget.

He said Mr Osborne had to "rebuild trust" in his Budget next month.

He urged him to include measures to ensure the tax system maximised recovery rates, that the industry was consulted on tax reforms and there were incentives for the decommissioning of oil installations.

Mr Salmond said: "The tax hike last year in the Budget, without consultation, damaged confidence as well as damaging economics."

Mr Salmond told the SCDI Oil and Gas conference in Edinburgh that the sector supported more than 200,000 jobs in Scotland and had been "an enormous success".

He added: "There is more than half of the economic impact of oil and gas still to be realised in the next 40 years."

The conference, which included industry leaders from Shell and BP, heard that about 24 billion barrels could still be extracted from the North Sea.