The cost of the US’s operations in Iraq and Afghanistan, together with wider efforts in the “war against terror”, could reach $2,400bn (£1,175bn, €1,700) over the next decade, with interest payments representing more than a quarter of the total, the US Congressional Budget Office said on Wednesday.

The figures, presented to the House of Representatives budget committee by Peter Orszag, the CBO’s director, are based on an assumption that US troops in Iraq and Afghanistan will be reduced to a total of 75,000 by 2013 and stay at that level for a further four years.