Coalition plans to expand 'manifesto for the Union'

The Treasury is spearheading the co-ordinated push, with Sir Nicholas MacPherson, the department's top civil servant, chairing a group of permanent secretaries.

It is overseeing teams of top economists and civil servants, who are busy formulating the statistical and policy ammunition for ministers, including David Cameron, to fire in their bid to stop the Nationalist-led attempt to end the 300-year-old Union. Sir Jeremy Heywood, the Cabinet Secretary, is also chairing another group liaising with ministers.

The documents, the first of which is expected within weeks, will look at a wide range of areas from the economy to defence and security.

But senior Coalition sources have made clear the project is flexible and can be enlarged as the date of the 2014 referendum approaches.

Insiders have told The Herald there is room for the manifesto to respond to events and to examine new issues that emerge as the independence debate intensifies.

The Coalition wants to ensure it can harness the expertise of the civil service on all aspects of the debate.

Some within the Coalition believe issues which could come to dominate the debate in the coming months have been barely touched upon.

The Scottish Government is also planning its own series of reports later this year – making the case for an independence.

In recent weeks there has been increasing controversy over a number of questions regarding independence, including the furore that surrounded Scottish ministers' calls for talks with Brussels about what would happen to Scotland's EU membership.

Five of the current "work streams" involve the Treasury and cover Scotland's economic performance, currency and monetary policy, tax and spending, financial services and banking, and debt and borrowing.

The other eight work streams involve a range of Whitehall departments, and include the legal basis and history of the Union; international issues; energy and North Sea oil; defence and security; welfare; culture, heritage and identity; immigration and borders; and business, innovation and infrastructure.

It is understood they will not provide definitive answers for what would happen in an independent Scotland on every issue.

Instead sources claimed they would point out the "likely" outcomes as well as the uncertainties of leaving the UK.

But the Scottish Government has denounced such tactics as scaremongering.

The SNP insists the more the UK Government sets out its case the more people will be won over to the case for independence.

The Scottish Government's own plans include 16 work streams focusing on every aspect of a newly independent Scotland, from security to welfare.

The SNP administration has said the projects would show how Scotland would make the transition to "a successful, independent country following a Yes vote for independence".

A spokesman for Deputy First Minister Nicola Sturgeon said the Scottish Government's reports would inform the upcoming White Paper on independence.

And he suggested that, in contrast to the UK Government's stance, this would lay out a positive case for leaving the UK.

He said: "Over the next 12 months we will lay out our ideas and open up for wider debate the ways in which the powers of independence can be used to address challenges in our economy and society.

"The work we are doing in government ahead of the publication of the White Paper is looking at the full range of responsibilities that would transfer to Scotland with independence and the opportunities that could flow from a Yes vote in 2014.

"Our current list of work streams has already been published and we will be setting out information and ideas throughout the year.

"Unlike the UK Government who have to try to justify the status quo, by tapping into the opportunities of independence we have a historic opportunity to harness the energy of our communities, our entrepreneurs and all those who are interested in finding Scottish solutions to long-standing challenges."