As many as 16 nurses at the troubled Ashworth Special Hospital - at present the subject of a public inquiry - had failed to re-register with their regulating body, the UK Central Council for Nursing, Midwifery and Health Visiting. Some patients at Ashworth - in Maghull, Merseyside - were also being detained illegally.
A spokesman for the council said the case was "potentially very dangerous" and a spokesman for the hospital said it was "serious" but that the situation had been remedied and all nurses were now registered.
Yesterday, a spokesman for the hospital said that patient care was not jeopardised by the lapse, and that it involved a handful of nurses out of the 900 employed, However, one ward manager has since been demoted as a result of the discovery.
The spokesman said systems for detecting such failings were now in place and the public should be reassured that the problem had been addressed several months ago. "Patients are at minimum risk to themselves and no risk to the staff or the wider public."
A spokesman for the UK Central Council said: "Any nurses practising without effective registration are by definition not subject to the council's standards.
"There is an onus on the individual to make sure they are up to date with their registration but there is also an onus on the employers as well to ensure there is a system in place to ensure that staff are up to date."
Ashworth - whose most notorious patient is Ian Brady, the Moors Murderer - has been under scrutiny since January 1997 when the then Secretary of State for Health, Stephen Dorrell, ordered an independent inquiry into the hospital over allegations involving pornography, drugs and paedophilia - particularly why a girl of eight was allegedly allowed to play with a sex offender.
The inquiry was told yesterday that Ashworth did not have a policy governing child visitors. Richard Backhouse, head of social work practices since February 1994, said the formulation of such a policy was "not high on people's agenda".
Mr Backhouse said he did not know why the recommendations of a Home Office and Department of Health leaflet published in 1991 giving guidelines for working with children had not been adopted at Ashworth. Nor did he know exactly what procedures were followed when Peter Hemming, a convicted paedophile, was allowed a home visit to the father of Child A, the young girl at the centre of the paedophile allegations within the hospital's personality disorder unit.
Referring to the vetting of visitors, Mr Backhouse said: "With hindsight I think we would have looked at it differently. At the time we were trying to put some structure into chaos.
"People were coming in who shouldn't have and people were being turned away who were perfectly safe."
Mr Backhouse told the inquiry he was kept in the dark about the concerns of nurses on the personality disorder unit, and was unaware that one of his principal social workers had been commissioned to work on an investigation into the admittance of Child A on to the unit's Lawrence Ward.Reuse content