The UK's national debt has risen above £1 trillion for the first time, but George Osborne is still on track to meet his target of reducing borrowing to £127bn by the end of the financial year.
Figures released by the Office for National Statistics on Tuesday showed that debt has risen to £1,003.9bn, or 64.2% of GDP, up from £883bn a year ago.
The £1 trillion mark was broken despite a bigger than expected fall in borrowing in December.
Public sector borrowing, excluding financial interventions such as bank bailouts, fell £2.2bn to £13.7bn in the month. Analysts in the City of London had expected it to fall to £14.9bn.
A Treasury spokesman laid the blame for the debt level at the feet of the previous Labour government.
"That our national debt has reached more than £1 trillion simply shows the unsustainable level of spending this country built up over the past few years, and shows why it is critical for our nation's future that we deal decisively with the deficit," they said.
"Today's figures show that we are making good progress, with borrowing over £11bn lower than in the same period last year."
The ONS said that the Treasury's coffers had been partially boosted by the increase in VAT and the levy placed on the banks.