The union says re-offending is lower than the Home Office suggests

NAPO said only 53% of people on probation re-offended within two years - not 60% as the Home Office said.

The government plans to privatise the Probation Service in a bid to improve its much-criticised performance.

The Home Office said it wanted the best provider - whether public, private or voluntary - to help stop reoffending.

The National Association of Probation Officers said the government's own "unadjusted" figures showed re-offending was less than Mr Reid said.

Assistant general secretary Harry Fletcher said reoffending by those on community sentences was at least 13% lower than those released from jail.

"The government is claiming that the Probation Service should be broken up because performance is bad and re-offending rates are too high.

"This does not appear to be the case."

He added: "It would appear that there are flaws in the argument and there is an urgent need for informed debate."

Poor performance

Mr Reid believe privatising the more routine tasks will improve the Probation Service.

He has also said he wanted to see up to �250m of the service's annual budget contracted out under new legislation after April 2008.

A Home Office spokeswoman said: "Protecting the public is our absolute priority, and we are committed to working towards an overall reduction in adult re-offending of 10% by the end of the decade.

"Criminals reoffend for a wide variety of reasons that cannot be tackled adequately by one agency alone.

"The Probation Service has delivered improvements in performance over recent years, but tackling re-offending requires a broad coalition of effort and a comprehensive but adaptable response."