The Conservatives have called for the early release policy to be scrapped
More than 50,000 criminals have been released from prison early under a scheme aimed at reducing overcrowding, Ministry of Justice (MoJ) figures show.
Since June 2007, 52,117 prisoners have been let out up to 18 days before the halfway point of their sentence.
The figure - for England and Wales - includes more than 10,000 violent criminals, although many serious offences are excluded from the scheme.
More than 1,000 alleged crimes were committed by people released early.
Those offences include three murders, rape, burglaries, muggings and sex offences.
Shadow justice secretary Dominic Grieve called for the early release policy to be scrapped.
"This is a direct result of Gordon Brown's reckless failure to provide enough prison places.
"Releasing criminals early has already resulted in three murders and over a thousand other crimes. It is unacceptable," he said.
Liberal Democrat home affairs spokesman David Howarth said: "The government was forced to introduce early release to deal with a prison population they had let get hopelessly out of control.
"Ministers must reduce the sky-high levels of reoffending if they are to regain control of the prison system."
Last month the former Lord Chief Justice Lord Woolf told the BBC public confidence in the criminal justice system was being eroded by the early release scheme.
The End of Custody Licence (ECL) was introduced 18 months ago to reduce inmate numbers at the height of the prison overcrowding crisis.
Lord Woolf said: "It's now being used routinely and we've got embedded in our system a situation of the judges sending prisoners into prison by the front door and the executive releasing them by the back door, and that doesn't make sense."
Among the total released since the policy was launched, 10,102 inmates convicted for violence were let out early, along with 1,262 robbers and 2,227 drug offenders.
Around 3,000 let out under the scheme were foreign national prisoners.
The government has paid £5.5m to prisoners released early, in part to compensate them for the cost of bed and board during the period in which they would have been incarcerated.
The current prison population stands at 82,586, up 707 from the previous year, the MoJ said.