An independent Scotland would inherit around 13 billion barrels of the current UK's oil and gas reserves but could see income from the North Sea plunge after 2018, an expert report has suggested.

Oil and gas consultancy Wood Mackenzie calculates that 84% of the 15.3 billion barrels of oil equivalent reserves remaining in the UK lie in Scottish waters.

The Edinburgh-based firm said production in Scottish waters could increase by around 10% to 1.3 million barrels per day in 2018, from the current 1.17m barrels daily this year, following huge investment by oil and gas giants like BP in areas such as West of Shetland.

However, it noted: "Post 2018, decline is forecast to set in once more with production dipping below 1 million barrels of oil equivalent per day (boe/d) by 2023, less than a quarter of the 1999 peak."

Wood Mackenzie's estimate of 15.3bn barrels remaining in UK waters is much lower than the 24bn barrels assumed by the Scottish Government.

In August, oil tycoon Sir Ian Wood said the Scottish Governmenthad over-estimated reserves of oil left under the North Seaby between 45-60%. He suggested there were about 15 billion to 16.5 billion barrels of recoverable oil left.

Industry body Oil & Gas UK thinks there could be 15bn to 24bn barrels remaining.

Wood Mack noted the lack of big discoveries in the North Sea in recent years and high operating costs put future Scottish production under pressure.

The consultancy said the industry would require stable taxes following independence. It highlighted the likely costs of decommissioning ageing oil and gas fields and associated platforms and pipelines.

"We estimate that by 2030 nearly US$9 billion of tax relief will be claimed in respect of decommissioning spend on Scottish fields," warned Wood Mackenzie.