Community service 'more effective'
Community service is more effective than short jail terms for low level repeat offenders, experts will say.
A report by campaign group Make Justice Work will be presented to Downing Street after a year-long study.
It is expected to say that offenders can find intensive periods of community service harder than a short spell in prison, and that the measure is more effective for persistent, low level offenders.
The report, called Community or Custody, was the result of a study led by a panel that included former Metropolitan Police Commissioner Sir Ian Blair, former Chief Inspector of Prisons Dame Anne Owers and chairman of the Magistrates' Association John Thornhill.
The inquiry team has interviewed victims of crime, ex-offenders, magistrates and prison staff and examined measures deemed alternatives to custody.
Make Justice Work says that 59% of adults who are given prison sentences of under 12 months are re-convicted within a year of being released.
The report will be published tomorrow morning and then presented at Downing Street at midday.
It comes after Justice Secretary Kenneth Clarke blasted a "feral underclass" of seasoned criminals for their involvement in the recent riots.
In a piece for The Guardian, he said: "In my view, the riots can be seen in part as an outburst of outrageous behaviour by the criminal classes - individuals and families familiar with the justice system, who haven't been changed by their past punishments."
He said that three-quarters of adults who were charged with involvement in the unrest already had criminal records.