An official report on a Kent prison has described it as "a disgrace" and warned some of its practices could be illegal.

Chief Inspector of Prisons Sir David Ramsbotham said Rochester Prison was guilty of "institutional neglect", and particularly criticised the treatment of asylum seekers, illegal immigrants and young offenders.

The young offenders' wing, in what was Britain's first Borstal, was described as filthy and infested with vermin.

Nearly 70 prisoners aged 17-21 years were living in a wing that was "filthy, vandalised, infested with vermin and subjected to an impoverished regime in which the only constant was unpredictability," Sir David's report said.

Almost half the population at Rochester Prison are asylum seekers, illegal immigrants or other foreign nationals.

Many of them speak little or no English, but Sir David said they were required to sign documents they do not understand with no proper translation facilities.

They are given no written explanation of why they are being held in prison or how long they will be there, the report said.

It highlighted the case of one new arrival from Albania who was put in a cell with a Pole who had been told to pass on the rules of the prison "because both names ended in an "i"," when they had no shared language.

And it questioned the legality of the practice of forcing prisoners to take drug tests, and punishing them if they refuse.

Sir David said the Prison Service needed to appoint an official to take responsibility for making sure foreign nationals were properly looked after.

The report did praise work done in the prison with sex offenders and a resettlement strategy which provided work opportunities for inmates after their release.

Comments refuted

Sir David said he would be returning in a year to monitor progress.

However, the report's finding that the jail was dirty was challenged by the Director General of the Prison Service, Martin Narey.

He categorically denied the jail was a "filthy establishment" and said he had recently made a lightning visit to the prison himself and found conditions "entirely satisfactory".

He also backed staff treatment of immigration detainees in difficult circumstances.

New immigration centres are being created which will mean detainees no longer have to be housed in jails.

And he insisted drug tests on detainees were lawful and necessary to maintain good discipline.