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.
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A mix of some showery outbreaks of rain and brighter spells in the west feeling cooler than Wednesday.
Showery outbreaks of rain will become more widespread through today, with heavy and locally thundery downpours possible.