The Scottish Government has announced cost-cutting changes to plans for a new road crossing the Forth River to resolve a funding battle between Holyrood and Westminster.

Scaled-down links between the southern end of the new bridge and the M9 will save roughly £2 billion, bringing the total cost of the project down from an estimated £4 billion.

The new bridge will serve as a complement to the existing crossing, prompting safety concerns regarding the ageing structure.

Early last week a row broke out between the Scottish Government and the UK Treasury after a request for a £2 billion cash advance to fund the project was rejected.

The SNP wanted to bring forward money that would be due to Scotland over the next twenty years, paying back the advance through smaller annual budgets.

However, Chancellor Alistair Darling made clear that this approach to funding would never be an option under the current administration when he spoke to BBC Radio Scotland’s The Business Programme.

He said: “We will work with the Scottish Government, but their particular scheme where they were asking to borrow money from budgets which are yet to be allocated over an extremely long period – that’s something that we simply don’t do.

“I think they ought to have been aware of it and they could have found out if they had asked earlier.”

The SNP’s manifesto made it clear that their administration would cease to use the much-criticised Public Finance Initiative to fund major public work and had pledged to set up the Scottish Futures Trust to replace PFI.

They have since stated that the SFT was only ever meant to support smaller-scale projects and that they had always intended to fund the new crossing through traditional public procurement.

Scottish Labour claim that the current situation proves the SFT is a failure.

Des McNulty, Labour’s transport spokesman, has branded the whole situation as "humiliating" for the current administration.

“The new crossing was the acid test for the SFT," he said. "Its failure imposes a huge burden on the capital budget in the period during which this project will have to be paid for.”

The debate was brought to a crisis point as the goverment said the crossing would instead need to be funded from the existing capital expenditure budget.

This would result in other construction projects such as schools, hospitals and road upgrades being pushed back or shelved entirely.

Further pressure has been heaped upon the Scottish Finance Secretary John Swinney for the way his department has handled securing funding for what is seen as a flagship project. The opposition has accused his department of waiting until the last minute to address the funding requirements despite having been in power for eighteen months.

Stewart Stevenson, the SNP transport minister announced to MSPs on December 10 that the bridge would be built using public procurement. However, it has since come to light that Mr Swinney had only written to the Treasury on 27 November, less than a fortnight before, and, at the point of Mr Stevenson’s announcement, had not yet received a reply.

Labour finance spokesperson Andy Kerr said John Swinney was guilty of incompetence and irresponsibility and called for a debate to take place.

“It beggars belief that John Swinney waited so long before contacting the Treasury on such an important project. He should come before Parliament and explain himself.

“The SNP repeatedly told us that the Scottish Futures Trust would be used to deliver the new crossing, but it has been clear for months that it is not fit for purpose. They should have opened talks much sooner to put a credible alternative in place.”

Mr Swinney is now facing damaging accusations that he is carrying out government activity based on party grudge and grievance rather than for the good of Scotland.

Instead of working together to find a mutually acceptable funding proposal, some see his approach to securing funding as an attempt to lay a political trap for the UK government, knowing that the request would be refused.

The Forth crossing became a priority for Scottish politicians when it became clear that corrosion of the supporting cables on the existing bridge would limit its load bearing capacity within the next decade.

Work on the new bridge is scheduled to start in 2011 with completion in 2016, a timescale that Stewart Stevenson again committed to, despite the current row.

“The Forth road bridge will happen, absolutely. It will happen... it has to and will come in on time in 2016.”