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In the press release Jacqui Smith, the Home Secretary, said there had been an overall fall in the number of people caught carrying knives and claimed that those found guilty of possessing knives were receiving longer sentences.

But the Home Office was unable to provide the statistics to support the claims saying they were “interim findings”.

A Home Office fact sheet claimed hospital admissions were down 27 per cent since the crackdown on knife crime in ten areas began in July and stated there had been 18 per cent fewer victims under 20 in London between April and September 2008 than in the same period in 2007.

Sources at the authority said Sir Michael was “furious” over the breach of the rules.

Sir Michael’s intervention follows concern in the Office for National Statistics at the way in which the Home Office has dealt with figures in politically sensitive areas such as crime and asylum and immigration.

It is the second time in recent months that the Home Office has been criticised over its use of statistics.

Professor David Hand, head of the Royal Statistical Society, highlighted “serious” bad practices during the release of immigration figures in August.

The latest row over is damaging for the Government as it once again casts doubt on whether people can believe official statistics on crime - an area where ministers are struggling to convince the public that offending is falling.

In October the Home Office was forced to admit that serious violent crime is much worse than they had been claiming because police forces had been failing to record offences properly.

Dominic Grieve, the shadow Home Secretary, said: “The knife crime epidemic is a tragedy that has claimed too many young lives.

"If government ministers have sanctioned the selective and manipulative spinning of these statistics, it is reckless and irresponsible.

"Labour should immediately publish the full figures so that we can see the truth."

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