The move, which comes amid an argument over Northern Rock’s liabilities appearing on the government’s books, is likely to provoke another political row about the projects, especially as Alistair Darling himself has been so critical of private sector off-balance sheet structures.

Government departments are resisting moves to switch to international accounting standards over fears of capital charges, a source familiar with government accounting said. ‘Government departments would incur a capital charge of 3.5% for bringing debt on to the balance sheet… which explains why departments would have a vested interest in keeping stuff off the balance sheet, unless the Treasury changes that rule.

They’re going to wriggle and squirm so as to not play by the same rules as those in the private sector.’

On 1 April, all government departments must make the change to IFRS. The Department of Health and the Ministry of Defence have admitted they will miss the deadline.