Net borrowing by the British public sector reached 14.41 billion pounds ($23.4 billion) in August, compared with 14.36 billion pounds in the same month last year.
The Office for National Statistics (ONS) data, which excludes financial sector interventions such as the government's preferred measure, showed the figure to be the highest for any August since records began in January 1993.
ONS data showed that public sector net debt was 1.03 trillion pounds at the end of August, equivalent to 66.1 per cent of the gross domestic product (GDP).
"The public sector current budget deficit amounted to 13.2 billion pounds last month, higher than the 12.8 billion pounds in August of last year," ONS said.
However, widened budget deficits have raised concern that the government could miss its deficit target for the year.
Britain's independent Office for Budget Responsibility (OBR) has set the government's borrowing target for the 2012-13 financial year, which began in April, at 120 billion pounds. Economists said that target now looked unattainable.
British public sector consists of four sub-sectors, namely central government, local government, non-financial public corporations and financial public corporations.