UK government borrowing in September hit the highest level for the month in five years, according to the latest official figures.

Borrowing – the difference between public spending and tax income – was £20.2bn in September, up £1.6bn from the same month last year, the Office for National Statistics (ONS) said.

The ONS said a rise in debt interest payments offset the increased amount the government had raised through tax and national insurance.

Borrowing over the first six months of the financial year has now reached £99.8bn, the ONS said, which is up £11.5bn from the same period last year.

The September figures continue a trend seen in August, when borrowing was also at its highest level for that month in five years.

The borrowing figure was slightly less than analysts’ expectations, but was roughly in line with what had been projected by the government’s official forecaster, the Office for Budget Responsibility, in March.

Although tax income was significantly higher than last year, in part due to the increase in employers’ national insurance contributions, spending also increased.

This was partly due to pay rises and inflation increasing the government’s day-to-day running costs, as well as inflation-linked increases to state benefits.

Responding to the figures, Chief Secretary to the Treasury James Murray said the government would “never play fast and loose with the public finances”.

He reiterated the government’s aim of bringing down borrowing, to be rid of “costly debt interest, instead putting that money into our NHS, schools and police”.