FINANCE Secretary John Swinney has agreed to update Scottish Government forecasts for North Sea oil revenues following claims they were over-optimistic.

Official figures produced a year ago predicted Scotland's share of North Sea tax revenues would amount to £34.6 billion.

However, the latest estimates from the independent Office for Budget Responsibility were last week downgraded to £18.8bn for the same period.

The figures prompted a series of calls for the Scottish Government to update its figures, which have been used repeatedly by ministers to make the case for independence.

Pressed again during a Holyrood debate yesterday, Mr Swinney said fresh forecasts would be produced "in the coming weeks".

He also promised to issue longer-range predictions, telling MSPs: "Now that more data is available we will extend those projections over a number of years."

Mr Swinney was responding to Tory finance spokesman Gavin Brown, who accused the SNP administration of using "highly questionable" figures.

In a report published alongside the Budget, the OBR revised its oil forecasts down by £3bn in the period to 2018/19, compared with its December predictions.

The figures widened the gulf between the Scottish Government's estimates, quoted in its independence White Paper, and statistics used by the UK Government.

In 2016/17, for example - the year it plans to declare independence - the Scottish Government's most cautious estimate is for a £6.8bn income from oil. The figure is more than double the OBR projection of £3.2bn.