The Prison Service today said there was a “minimal risk” of a mystery illness which swept through HMP Wandsworth spreading to the community.

The cause of the diarrhoea and sickness illness, which the Prison Service now says has infected 324 prisoners and a small number of staff, is still being investigated by public health officials.

Like yesterday, inmates are being kept away from court today and visitation has been cancelled to limit potential spread of the sickness.

A Prison Service spokesman said: “As of Thursday evening, 324 prisoners and a small number of staff at HMP Wandsworth had been taken ill with diarrhoea and sickness.

“Tests are being conducted by local health officials to confirm the nature of the outbreak.

“Prisoners will not be attending court on Friday, September 18, and visits to the prison will not be taking place. This is a precaution to limit any potential spread.

“The prison is dealing with this incident together with local health officials in line with standard infection control procedures.

“We would like to reassure the public that there is minimal risk that this illness could spread from the prison to the community.”

The Prison Service yesterday revealed that 370 inmates and a “small number” of staff became ill with diarrhoea and sickness.

Some staff arriving at the Heathfield Road prison for work on Thursday morning were told to go home.

Sources inside the prison claimed prisoners had been complaining of severe flu-like symptoms before suffering from diarrhoea.

They also claimed an inmate who died this week had been on E wing, which allegedly had the highest number of prisoners falling ill.

A Prison Service spokesman said the death was unconnected to the outbreak but refused to confirm whether the new arrivals E wing was at the centre of the outbreak.

The Prison Service has also refused to comment on whether the outbreak could be linked with swine flu.