Increase to £17.8bn is well above City forecasts and is highest December figure for four years
The cost of UK government borrowing unexpectedly jumped to £17.8bn last month, piling pressure on Rachel Reeves to plan budget cuts before a spending review in the summer.
The figure was about a quarter higher than the City had forecast and was up by £10.1bn more than in the same month a year earlier, making it the highest December borrowing for four years.