Almost two thirds of serious repeat offenders avoided a fresh prison sentence for newly committed crimes last year, a new report claims.
The Centre for Crime Prevention research, which the Ministry of Justice said was "highly selective", said 91,032 criminals with at least 10 previous convictions avoided being sent to prison in the 2011-2012 financial year, 64.9% of the 140,168 freshly found guilty of a crime.
The figure amounts to more than the current prison population of the UK of 83,825 and the report claims offenders received fines, community service or a fully suspended sentence for crimes including violence against the person, theft and sexual offences.
Peter Cuthbertson, the centre's chief executive and the report author, said: "These figures show the appalling failure of soft sentencing.
"Fines, community service and suspended sentences leave criminals free to commit more crimes. They should be reserved for minor offenders. But these figures show they are the only punishment for tens of thousands of hardened criminals every year."
The report claims that in 2011/2012 68,100 out of 108,119 offenders with more than 15 previous convictions, some 62.9%, received a penalty other than prison. This was compared to 49,729 in 2006/07, an increase of 38%.
It said the number of fully suspended sentences increased 31-fold for offenders with 15 or more previous convictions/cautions in the decade from 2001/02, from 270 to 8,284.
The report said 11,810 serious offenders received with 15 or more previous convictions received discharges and 20,879 received a community. Some 16,111 received a fine. Of those who did go to prison, the report claimed, the average sentence was one year and five months.
Mr Cuthbertson said the Government's proposal to close several prisons and build a new "super-prison", announced last week by Justice Secretary Chris Grayling, was "a step in the right direction".
A Ministry of Justice spokesman said: "These figures are highly selective. They fail to recognise that the average prison sentence length has increased by more than a year in the past decade and the use of out of court disposals is down by nearly 40%."