More than 2,600 prisoners let out early this month to ease overcrowding

The total - 2,612 - is the largest monthly number since the policy was introduced in June and represents an increase of one fifth on last month's total.

Governors were under pressure to find every eligible candidate and those released 18 days before half their sentence had been run during October included 495 violent thugs, 50 robbers, 241 burglars and even two sex offenders.

The total released since June this year is 11,132.

Tory justice spokesman Nick Herbert said: "Early release of offenders has put the public at risk but has not dealt with prison overcrowding.

"When Gordon Brown became Prime Minister, he claimed that he believed in punishing offenders. In fact he has already given 11,000 criminals a break."

Ministers introduced the so-called 'end of custody licence' scheme in June as the prison population in England and Wales reached crisis point.

Offenders can be set free 18 days before the usual halfway-stage of their sentences to create space in the crowded jails.

The prison population yesterday stood at 81,459 - only a few hundred spaces short of bursting point.

Earlier this week, it emerged Ministers had quietly scaled back a desperately needed prisonbuilding programme.

In January Labour pledged to build 2,500 extra spaces by the end of this year. But figures slipped out in a Parliamentary answer earlier this week revealed that only 1,700 will be completed and inmates will continue to be locked in police cells - at a cost to the taxpayer of £400 each every night.

The Government blamed problems over planning permission and said the places would still be completed at a future date.