Lewes Prison has the worst drugs record in the country, according to a report released today.

The jail had 31.6 per cent of random drug tests prove positive last year, more than any other jail in England and Wales.

Today's report, by the Prison Reform Trust, is the second this year to criticise the jail.

It also criticises Lewes for failing to provide enough "purposeful activity" for prisoners.

The number of assaults by prisoners is creeping up to the Prison Service's accepted level.

Lewes MP Norman Baker said: "The figures show the drastic need for improvements at the prison."

Suicide levels are not included in this year's report. Five prisoners have taken their own lives at the jail during the last 16 months.

Prison governor Paul Carroll said action was being taken to reduce drug misuse and investment in the jail should show improvements in all areas next year.

Of the positive drug tests, 21.1 per cent showed prisoners had been using cannabis and 13.7 per cent included traces of harder drugs, including heroin.

The 31.6 per cent is way above average when compared with other jails and almost three times higher than the 12 per cent target rate of positive testing within the Prison Service.

Mr Carroll agreed with the figures but said they were distorted because one of his own prison officers was peddling drugs inside the jail for a year.

In March, Andrew Hubbard, 39, was jailed for seven years for operating a "mini drugs supermarket" behind bars.

So far this year, the number of prisoners testing positive has dropped to 12 per cent.

The jail has an average 530 prisoners at any one time, just below its maximum capacity of 553.

Last year it provided an average of 18.6 hours of purposeful activity per prisoner a week, compared with the Prison Service's performance target of 24 hours each week.

The damp Victorian building, parts of which date back to 1853, fares badly in categories assessed by the Prison Reform Trust, which seeks to improve conditions for the country's prison population.

It is only just below the Prison Service's accepted level of assaults by prisoners.

Lewes recorded a rate of 7.8 per cent. The Prison Service says the key performance target level should be nine per cent.

Mr Carroll, who was brought in 16 months ago, said: "I accept the figures because they have all been provided by us. The drugs figure is high because it includes a period when one of our own officers was peddling drugs inside the prison. He is now serving a prison sentence.

"We have taken action to reduce the level of drug misuse and this is already showing results.

"With regard to assaults on staff, there has only been what I regard as one serious assault on a member of staff last year, the rest have involved instances when prison officers have stepped in to stop trouble between prisoners.

"Regarding the amount of activity for prisoners, we have increased this and we are now just above the accepted key performance level targets laid down by the Prison Service.

"Substantial investment is being put into Lewes Prison, which I welcome, and we should see improvements in all these figures next year."

Mr Baker, who has been calling for improvements to the jail, said: "I welcome the reduction in the number of prisoners testing positive for drugs so far this year. I accept the drug figures must have been distorted by a prison officer peddling drugs.

"The governor has introduced some improvements but the Government should realise Lewes needs to have a substantial amount of money spent on it."

Lewes caters for Category B prisoners and remand prisoners. It is classed as a high-security local prison.

A Board of Visitors report in April found two inmates living and eating in a small cell with an open lavatory, damp walls and little daylight. Conditions were described as "Dickensian", "appalling" and "inhumane".

The latest report shows Sussex's only other prison, Ford open prison near Littlehampton, had no recorded assaults on prison officers last year.

Seven per cent of Ford prisoners tested in random drug sampling proved positive. Ford provides fewer than 40 hours of purposeful activity per prisoner each week.