SCOTLAND'S share of North Sea oil revenues amounted to £4 billion last financial year - considerably lower than Scottish Government estimates, new figures have revealed.

The total for 2013/14 was down £1.5bn on the previous year, according to official public-sector revenue figures published yesterday by the Scottish Government.

In a key report last year used as the basis for the SNP's independence White Paper, the Scottish Government estimated oil revenues for 2013/14 at between £6.2bn and £8.3bn.

The latest figures were published on the Scottish Government website yesterday without comment from ministers.

Scottish Conservative finance spokesman Gavin Brown MSP said: "The Scottish Government has managed to seriously undermine its own case for separation by inadvertently publishing these figures.

"It clearly wanted to keep a lid on these very disappointing statistics until after the referendum, and that's now impossible."

He added: "The Scottish Government has to now explain why it got these estimates so spectacularly wrong, for the second year in a row."

A spokeswoman said the Scottish Government Oil and Gas Analytical Bulletin published in May this year predicted rising North Sea revenues in future years.

The Government spokeswoman said: "The bulletin made clear that record levels of investment in the North Sea will reduce revenues in the short term.

"However it also highlighted that this investment will allow new fields to come on stream and in turn increase production and revenues."