St Helens Council conducted hundreds of enquiries into reports of abuse and neglect in care homes last year, new figures show.
Charity Age UK has called for a zero-tolerance approach to abuse, after "deeply distressing" figures revealed an increase in investigations of maltreatment of elderly people across England.
If councils believe an adult with care and support needs is experiencing or is at risk of abuse or neglect, they must carry out what is known as a Section 42 enquiry, to determine whether they need to step in.
Figures released by NHS Digital reveal St Helens Borough Council completed 410 such enquiries into incidents occurring in care homes in 2018-19.
The enquiries – which can also be carried out for suspected abuse occurring in other settings, such as hospitals or a victim's own home – may concern allegations of physical, sexual, psychological or financial abuse, as well as neglect and substandard care.
Across England, people aged 85 and over were 20 times more likely to be the subject of a Section 42 enquiry than those aged between 18 and 64.
In St Helens, one in every 17 people aged 85 or over were involved in an enquiry, compared to one in every 351 under 65s.
Caroline Abrahams, director of Age UK, said the figures were "deeply distressing".
She said: "Some older people are being badly let down by a system that has failed to treat them with respect or protect them from abuse and neglect and this urgently needs to change.
"Care homes must adhere to the strict rules and procedures which are devised to help prevent problems such as abuse, poor management and neglect.
"Any abuse, whether neglect, financial manipulation or physical or mental cruelty, is unacceptable and deserves a zero-tolerance approach.
"We would encourage anyone who suspects that someone is being abused to contact their social services department or the police straight away."
The number of enquiries carried out in care homes in St Helens increased by 1% compared to the previous year, when there were 405.
Across England, the number of cases rose by 6% over the same period, climbing to 47,535.
The likelihood of a person aged 85 and over being the subject of an enquiry has also increased across England, rising from one in 43 during 2017-18 to one in 41 last year.
The Care Quality Commission, which inspects and regulates care homes, said it was unacceptable for vulnerable people to experience poor care.
Kate Terroni, chief inspector of adult social care, said: “People deserve to be treated with dignity and respect and for their human rights to be protected at all times.
"We know that most people working in caring professions are dedicated and passionate about what they do, but we also know that this is not always the case.
"We will continue to work with providers to encourage them to improve but where this does not happen we will use our enforcement powers in people's best interests and take action when necessary."
Overall, 1,890 safeguarding concerns were raised about vulnerable adults in St Helens during the year, and 1,275 Section 42 enquiries completed.