Broadmoor Hospital issued with CQC warning notice over staffing
A lack of qualified nurses was "affecting the care and treatment" of patients at Broadmoor Hospital, the health watchdog has found.
The Care Quality Commission (CQC) said there were 68 vacancies at the high security facility - almost a third of the required staffing.
It issued West London Mental Health NHS Trust with a warning notice.
The trust said it was "acting swiftly" to improve recruitment but faced difficulties "like many NHS trusts".
The CQC inspection was carried out in November to check on progress on issues highlighted in a previous report.
Dr Paul Lelliott, CQC deputy chief inspector of hospitals, said the trust "must improve the quality of care that it provides to patients".
"Specifically, our inspection team found that there were 68 vacancies for qualified nurses ... this was affecting the care and treatment of patients."
The CQC's full report is due in January.
A spokesperson for West London Mental Health NHS Trust insisted improvements had been made since a report in June 2015.
"Like many other NHS trusts we face difficulties in recruiting suitably qualified, specialist registered mental health nurses and other clinical staff."
He said measures had been put in place to improve recruitment and retention of staff. These included relocation packages for nurses and career development for healthcare assistants wanting to become qualified nurses.
Broadmoor, which has housed infamous killers including Peter Sutcliffe and Graham Young, is currently undergoing a £242m overhaul in a bid to move away from its image as an outdated Victorian institute.