The Care Quality Commission has issued a formal warning to Avon and Wiltshire Mental Health Partnership over levels of staffing at Blackberry Hill Hospital in Bristol.
It followed an unannounced inspection of three wards at the Fromeside Unit in December. The medium secure unit provides specialist care and treatment for adults with mental disorders, which may mean that they are at significant risk of harming themselves or others.
Inspectors found that the unit was failing to comply with the national regulation on staffing and did not have not enough qualified, skilled or experienced staff to meet people's needs.
More top news
Devon's MPs have called for increased funding for the county's schools. They believe they're underfunded compared to elsewhere in the UK.
It's ten years since the MSC Napoli was beached deliberately in Lyme Bay - prompting unforgettable scenes of beachcombing.
Barriers have been put up across the entrance to the former BHS in Exeter just weeks after several homeless people started sleeping there.