The Prison Service failed to reach its target of getting just over a fifth of jailed sex offenders to undergo treatment programmes last year.

Just 839 of the five thousand sex criminals in prisons in England and Wales completed the programme, 300 below the required number.

It was one of six areas where the Prison Service failed to meet its performance target, according to the Prison Reform Trust's (PRT) analysis of figures from the service's annual report.

The PRT blames the failure to meet the targets on overcrowding, which it said was threatening to "paralyse" the entire system.

The Prison Service measures its success against a series of 15 targets called Key Performance Indicators.

One of them is the number of inmates expected to undergo sex offender treatment programmes.

In all, 4161 convicted sex offenders went without treatment last year.

A Prison Service spokeswoman said the target had been too ambitious.

A disturbing number of prisons are overcrowded, unsafe and provide inadequate purposeful activity for prisoners

Joe Levenson PRT

There were also problems recruiting and training psychologists to run the programmes, she added.

The results also showed the number of attacks by prisoners exceeded the target figure.

Assaults on prisoners were 10% higher than the target, with 6,684 incidents in 2001-02.

According to the figures, assault rates tended to be higher in young offender institutions.

The results also showed more than half of all prisons in England and Wales failed to give inmates something constructive to do for more than a day a week.

The PRT said as a result inmates are leaving prison unprepared and likely to reoffend.

The author of the PRT's report, Joe Levenson, said: "The Prison Service is struggling to cope with a record prison population.

"A disturbing number of prisons are overcrowded, unsafe and provide inadequate purposeful activity for prisoners.

"Until these failing prisons are drastically improved, prisoners will continue to be held in damaging conditions with little done to prepare them for release."

Drugs tests

Targets that were met include a reduction in the number of positive drugs tests among prisoners.

They fell to 11.6%, just below the Prison Service's 12% target.

A Prison Service spokesman admitted the increased prison population was putting a strain on the system.

"The Prison Service has no control over the number of prisoners sent to it by the courts," she said.

"The prison population has recently reached record levels.

"An increased population puts inevitable strain on prisons - the level of overcrowding increases, resources are stretched and prisons struggle to deliver the core regime."

Where the Prison Service is failing
PERFORMANCE INDICATORS	TARGET	CURRENT FIGURE
Assault rates	9%	9.9%
Sex offenders taking treatment programme	1,160	839
Prisoners' purposeful activity, per week	24 hours	23.4 hours
Staff sick leave taken	10 working days	13.9 working days
Cost of a place in prison	£36,323	£36,377
Prisoners' basic skill awards, level 2	18,000	16,133