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
A man who is having his leg amputated is inviting people to enter a competition to guess the weight of his amputated leg for charity.
People are gathering in Castle Park in Bristol for a march urging leaders to take action against climate change. It's ahead of a UN summit.
Crowds of people have already been descending on Bath for the first weekend of their famous Christmas Market.