Researchers say Lewes prison has the worst drugs record in England and Wales.

Almost one in every three drug tests at the prison were positive, the annual report of the Prison Service revealed.

The 31.6 per cent positive testing rate was the highest in the country - with some male prisons recording figures below four per cent.

The next highest testing rate after Lewes was 27.5 per cent at Blakenhurst prison.

Lewes MP Norman Baker said: "Communities expect people to go to prison to pay a penalty and be rehabilitated - not to join a drug den."

"This is a very serious statistic which gives great cause for concern.

"I have been aware for some time of the drugs problem at the prison and I know the governor has been taking steps to deal with it.

"But quite clearly these figures are unacceptable.

"Prison is a closed environment by definition and it ought to be easier to control drugs inside rather than outside."

Governor Paul Carroll said the number of positive drug tests at the jail had now been cut to 12 per cent.

He said the figures related to the year to April and a zero tolerance policy on drugs was having an effect.

Mr Carroll said more drugs workers had been employed in the prison, an amnesty bin provided for new inmates to leave drugs and there were tougher searches of prisoners, visitors and staff entering the prison.

He said: "Over the past 12 months significant steps have been taken to put in place new measures which started to have an impact over the first three months of this year."

The report also reveals 7.8 per cent of the prisoners who were sent to the jail between April 2001 and March this year suffered an assault by another inmate.

The total number of attacks was 36.