They are also critical of legislation in the current Criminal Justice Bill, which is described as reversing many previous improvements to the service.
In the Association of Chief Officers of Probation's annual report published today, Anne Mace, the group's chair, says a consistent criminal justice policy has been replaced by a 'sound-bite campaign, characterised by the slogan 'prison works' '.
She argues that the Government's emphasis on the greater use of prison along with stiffer penalties is flawed. 'Harsher penalties are largely irrelevant to the level of crime, and changes in sentencing have no measurable effects on crime rates when less than 5 per cent of recorded crime reaches the courts.
'Punishment has its place but it is impoverished as an end in itself and will rarely bring about the behaviour changes desired.'
Her comments come as the prison population reaches new highs, with more than 50,000 people expected to be incarcerated by the end of the year.
The report also notes that some of the amendments introduced to the Criminal Justice Bill have reversed 'many of the constructive and beneficial changes introduced' in 1991.
The association is also critical of the Home Office's new three-year plan for the probation service, which it does not believe is 'part of any coherent or positive strategy seriously aimed at the long-term and genuine reduction of crime or the fear of crime'.