The value of the UK government's debt has grown to 84% of the country's economy for the first time, according to the Office for National Statistics (ONS).
Public sector debt rose £84 billion to £1.62 trillion in June - the equivalent of 84% of the size of the UK economy.
Borrowing fell £2.2bn to £7.8bn in June, compared with the same period last year. For the financial year so far, the UK government has borrowed £25.6bn, down £2.3bn from the same point last year.
The ONS stressed that volatility makes monthly figures less reliable, with year-to-date figures a more reliable indicator of performance.
Chancellor Philip Hammond said: "These public finance figures highlight the underlying strength of the British economy. Ahead of the referendum monthly borrowing continued to fall, with the deficit in June the lowest it has been since 2007.
"As our economy now adjusts to reflect the referendum decision it is clear we will do so from a position of economic strength."