The government today apologised for a gargantuan error on obesity figures, admitting that contrary to its claim earlier this week that there were 900,000 obese incapacity benefit claimants, in fact there are only 900.

This means that the average amount paid out in England every week is £70,965 rather than the £70,965,000 health minister Lord Warner claimed. The Department of Health blamed an "administrative error" for the mistake.

In a statement, officials said: "The department apologises for this error and any difficulties this may have caused.

"The department is taking action through parliamentary channels to rectify the mistake."

It comes as reports suggest Downing Street has rejected proposals for a "fat tax" on unhealthy food.

However, the fact remains that 70% of men and 63% of women were estimated to be overweight in 2002, and levels of child obesity have been branded an "epidemic" by health experts.

Last week the health secretary, John Reid, called for better labelling of fatty foods as part of a drive to tackle obesity and the this week announced a voucher scheme to entitle low income families to free fruit and vegetables.

Alarm is mounting in the Treasury and the Cabinet Office that a failure to slim the nation could lead to a public spending crisis in Whitehall.