Debt as a percentage of gross domestic product (GDP) - a broad measure for the total economy - hit 65% in May, up from 61.3% last year.
April's borrowing figures were flattered by a one-off £28 billion lift from the value of assets transferred from the Royal Mail pension plan.
But excluding this one-off impact, total borrowing for the current financial year stands at £28.4 billion.
Earlier this month, the Chancellor and Governor of the Bank of England Sir Mervyn King unveiled a multibillion-pound lending scheme to stimulate economic growth - but ministers insisted the move was not a "Plan B".
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ITV News Economics Editor Noreena Hertz said an economic slowdown looms as a fall in retail spending led to gloomy figures.
Detectives in Westminster are investigating after the man was discovered on the Route 189 bus in Marylebone shortly after midnight.
The murderer was shaking and appeared to be gasping for air for around 13 minutes before dying.