AN independent Scotland could demand the UK pays the new state to cover the decommissioning costs of North Sea Oil, according to a think tank report published today.

The analysis by the Institute for Government said such a request from Edinburgh would be legitimate as the UK had benefited substantially from tax revenues generated from the resource.

It added that the move would help improve the starting point of the finances of an independent Scotland.

Amid the growing tensions across the UK, the IFG study, entitled "The fiscal position of Scotland, Wales and Northern Ireland", examines what the size of its deficit would be if Scotland and Wales became independent and Northern Ireland left the Union to join the Republic of Ireland.

READ MORE: Labour plotted to steal Scottish oil and change marine borders to stop indy

"All four constituent nations of the UK generate a similar level of revenues relative to the size of their economies. But because the economies of Wales and Northern Ireland are substantially weaker than those of England and Scotland, they generate far less revenue per person in cash terms," it said.

"These differences resulted in England having a public sector deficit of 0.3% of GDP in 2018/19, compared to 7.7% in Scotland, 17.9% in Wales and 19.0% in Northern Ireland.”

The report does not point out that the only part of the UK to have become independent in the last 100 years – the Irish Republic – is the only part to have a fiscal surplus (of 100m euros in January 2019).

It goes on to add each of the deficits could be cut by legitimately demanding future payments in a range of areas from the UK

"Future payments from the rest of the UK: There are some arguments for the remainder of the UK to make payments in future to meet some of the costs of spending that is classed above as being for the benefit of Scotland, Wales or Northern Ireland," it said.

READ MORE: Second study says Scotland can afford to be independent

"Such payments could reduce the deficit faced by the new country. For example, an independent Scotland could seek support from the rest of the UK for North Sea decommissioning costs since the UK as a whole benefited from the taxes generated by the past extraction of oil and gas."

"If English pensioners retire to Wales in future, their pension costs could be met by the UK, rather than by the Welsh government (to the extent that those pension rights were accrued after Welsh secession) – just as the UK currently pays the pensions of those who retire abroad.

"However, Sinn Fein’s suggestion that the entire cost of future state pension payments in Northern Ireland should be met by the rest of the UK (including those that have already been built up) because “the people of the North have already accrued pension rights by way of their national insurance contributions” ignores the fact that the UK state pension system works on a pay as you go basis.

"Again, these settlements would need to be negotiated with the rest of the UK on secession."

READ MORE: IFS: Scotland is a 'rich country' which could become independent

The estimated bill for decommissioning North Sea oil and gas infrastructure is still expected to cost £51 billion, according to an official estimates for 2018.

The Oil & Gas Authority said that the likely bill had been reduced by £9 billion because of "continued improvement in planning and execution practices" and despite the fact that more infrastructure had been built since its original estimate of almost £60 billion in 2017.

It said that these improvements had cut the estimated costs of plugging and abandoning wells and removing platforms and subsea infrastructure. The authority is the government owned body that regulates the industry and oversees decommissioning.

More than 300 oil and gas installations such as production platforms exist in UK waters and many are coming to the end of their lives as old fields are exhausted. Taxpayers will be on the hook for a big share of the bill for removing the infrastructure through a system of tax relief. Based on the 2018 estimate, which put the clean-up bill at £58.3 billion, the cost to the public was put at £24 billion.

In 2017 the authority set a target with industry of slashing the eventual decommissioning costs by 35%.

Last week The National reported that Labour ministers in the late 1970s drew up secret plans create a new maritime border which would include hiving off Shetland – and possibly Orkney – from an independent Scotland in order to bring North Sea oil into “English waters” as part of a covert campaign to scupper independence.

The proposals emerged in newly released documents from the government led by Jim Callaghan.