Half a million crimes committed by serial offenders who have just left prison

Ministry of Justice figures show that an estimated 155,000 criminals a year, or four in ten, re-offend within 12 months of release, not including the fast-growing numbers being let off by police with a caution or on-the-spot fine instead of being charged.

The proportion of juvenile criminals who are convicted again has risen year-on-year, and the Government has missed its target of cutting numbers by five per cent from 2000 to 2006.

Behind bars: But nearly half of prisoners find themselves headed back in the direction of prison within a year

The disturbing figures, highlighting the extent of so-called ' revolving door' justice, were produced by tracking the 51,157 adults and 48,938 juveniles who were released from jail or began community punishments in the first three months of 2006.

Rising numbers of criminals being sentenced meant these 'cohorts' were substantially bigger than in 2005 - up 15 per for adults and eight per cent for juveniles.

Among adults 39 per cent were re-convicted of another crime within 12 months, slightly down on 2005, while for juveniles the rate rose slightly to 38.7 per cent.

The overall number caught re-offending was equivalent to 155,560 criminals over 12 months, an increase of 8.5 per cent on the previous year. With many criminals being caught several times, there were 146 offences for every 100 adults in the cohort, and 123 crimes per 100 juveniles.

That equates to almost 540,000 crimes committed over 12 months, up 3.3 per cent on the previous year. The crimes include an estimated 92,384 cases of violence, 3,392 serious assaults and 1,700 sexual offences.

The real picture is far worse as many crimes go undetected, and the Ministry of Justice figures do not include criminals let off with a caution or instant fine or formal warning, or court cases which are not yet completed.

The Ministry of Justice said the figures showed that the proportion of criminals who are re-convicted and the number of re-convictions per 100 offenders had dropped since 2000.

Come and go as you please: Four in ten prisoners appear back for the courts within a year of release

Justice minister David Hanson said: 'We have made considerable progress in protecting the public by reducing reoffending but there is more work to be done.'

The re-offending figures emerged as one of Britain's most senior police officers warned that Labour policies had gravely undermined confidence in the criminal justice system, both among the public and police.

In a withering assessment Mike Fuller, Chief Constable of Kent Police, warned that criminals were avoiding jail or being freed early because of the shortage of prison places, a crisis which he claimed ministers should have foreseen five years ago.

Mr Fuller, who is seen as a leading contender for Britain's top policing job of Metropolitan Commissioner, said: 'Sentencing policy would appear to be determined more by the number of prison places rather than the seriousness of the crimes people have committed.

'The Government has underestimated how important sentencing is to public confidence.'

Case study                                                                                                

Less than a week after he was released from jail, Andrew Mournian battered his girlfriend to death.

Mournian, 36, had been jailed for 20 weeks for an earlier attack on Amanda Murphy but was allowed to leave prison early through the End of Custody Licence scheme.

Five days later Mournian assaulted 47-year-old Miss Murphy, a mother of two, at their home in Dewsbury, West Yorkshire. She was so badly beaten that her mother could hardly recognise her, and she died three days later from brain injuries.

Mournian, an alcoholic and heroin user, had been jailed five times before. In 2005 he served a 12-month sentence for attacking an ex-girlfriend with a beer bottle.

When police arrested him for the murder of Miss Murphy he told them he had repeatedly smashed her around the head, claiming he had discovered she had been sleeping with his brother while he was in prison.

He was jailed for life last December at Leeds Crown Court.