Police are “abusing” powers to detain people under the Mental Health Act unnecessarily, a West Midlands inspector has warned.

But officers are also forced to take people with mental health issues into custody – because the NHS refuses to take responsibility for them, a House of Commons inquiry was told.

The concerns were raised by Inspector Michael Brown, in a submission to a probe into policing and mental health.

Inspector Brown has worked across Birmingham and the Black Country and spent three years as a specialist on policing and mental health for West Midlands Police.

He has also advised forces across England and Wales and Wales on how to improve the way they deal with mental health issues.

His blog, mentalhealthcop.wordpress.com, received an award from mental health charity Mind and his Twitter account, @mentalhealthcop, has more than 20,000 followers.

However, he hit controversy earlier this year when his Twitter stream was suspended by West Midlands Police amid allegations of being critical of the force. But after an investigation, and a huge public outcry, it was reinstated.

In evidence to the Home Affairs Select Committee, Insp Brown warned that police officers frequently dealt with people with mental health issues but lacked the training needed to help them.

Inspector Brown said: “My own estimates as well as other limited research suggest that the number of people arrested for substantive offences who may be experiencing a serious mental health problem equates to between 25 per cent and 40 per cent of all those detained.”

He added: “In my day-to-day role as a police emergency response inspector, my team deal with mental health crisis situations almost every shift, frequently many of them in a single day.

“It is a larger feature of my day-to-day work than robbery or burglary.”

Most officers receive only up to eight hours of training on mental health issues at the start of their careers which is supposed to cover everything from the law to understanding different illnesses that exist.

Further training is often provided by local health trusts, Inspector Brown said, but many of the mental health professionals involved don’t appear to understand the law. He warned: “Having witnessed training provided by mental health trusts, I have also been alarmed at how wrong some of it is, legally speaking.”

Police were detaining people under the Mental Health Act unnecessarily, he warned. “The police in some areas massively overuse and occasionally abuse, section 136 of the Mental Health Act.”

Only 17 per cent of people detained by police under the Act are later detained by the NHS, he said – and in one force in the north of England this was fewer than 10 per cent.

“This suggests very strongly officers in that force are misapplying the power and need further direction and training.”

He added: “We need better training for officers, in my view. Otherwise, we are expecting the NHS mental health crisis system to operate as a dumping ground for problems the police wish to push elsewhere.”

But Inspector Brown also warned that health services and police were failing to work together. For example, the Mental Health Act gives police the power remove a person with a mental disorder from a public place to a “place of safety”, but officers are not supposed to use a cell or holding room unless there is no alternative.

In some cases, an A&E unit would be an appropriate “place of safety” but hospitals were refusing to accept referrals, Inspector Brown said.

It means officers might be forced to take cases such as “an elderly person with dementia or a 15-year-old girl with depression” into custody even though it was clearly not the best place for them.

And police struggled to obtain medical help for people who were violent, or had drug or alcohol issues, he said.

He expressed “alarm” about “street triage” schemes, which see police officers and medical professionals working together to respond to situations, both in public places such as streets and in people’s homes.

These led to people going into police custody who actually needed medical help, because both nurses and police officers often agreed that “custody is the only place that could safely contain” aggressive people.