Britain’s biggest police force received a phone call relating to mental health every five minutes last year, an escalating level of demand caused by NHS services struggling to cope.

The number of calls handled by the Metropolitan police in which someone was concerned about a person’s mental health hit a record 115,000 in the last year: on average 315 a day, or about 13 an hour.

Volumes have grown by nearly a third since 2011-12, according to data released under freedom of information legislation, and officers fear the demand for help from the public will continue to increase.

One senior police officer told the Guardian a reduction in the ability to cope of NHS mental health services was a key factor in the rise in mental health calls to the police, and it was a national trend.

Insp Michael Brown, mental health coordinator for the College of Policing, said police had become better at recording such calls but this could not account for the big rise.

“We know there is more demand on NHS mental health services and their funding has been cut,” he said.

“We know that there has been a 60% increase in referrals to NHS mental health crisis teams but these services have had a cut in their funding.”

Police officers say they end up picking up the pieces, with the NHS unable to help enough people under its care.

Brown said: “Most people in contact with police about mental health issues don’t need the police, they need a mental health professional.

“The inability to access a mental health professional is the problem, and that generates a lot of work for the police.”

In some cases, ill people struggling to find help commit crimes to obtain treatment. A woman on crutches walked a mile to smash a shop window in Hereford, then called the police herself, believing that was the best way to get access to mental health services.

Across England and Wales, police forces also report that they are increasingly being asked to become involved with mental health issues.

As yet unpublished internal figures about the number of times powers are used to detain people under mental health legislation are also expected to be at record levels when they are released later this year.

The Guardian understands police use of mental health detention powers across England and Wales will rise again when the latest figures are published later this year, having hit 28,271 in 2015-16.

In 2005-06, the power was used 17,417 times, illustrating the growth in demand for police involvement. Police fear it will be a continuing trend.

The Met also expects to use powers to detain under section 136 of the Mental Health Act much more frequently in the years to come.

Commander Richard Smith, head of safeguarding at the Met, said: “Based on current trends, section 136 demand is set to double in London in the next 10 years as it’s increasing by approximately 10% each year.”

Smith added: “The issues we deal with include those with mental ill health who are involved in crime as victims or suspects as well as people who are in crisis in their home or in a public place.”

Nationally, police believe a significant number of those about whom they get calls are already under the care of NHS mental health services, or have been, which is beginning to have an effect on policing.

In West Yorkshire, mental health nurses are being employed in two custody suites to help with people brought in by officers. The force says the mental health incidents it deals with every month have risen to 1,300, up from 850 two years ago.

Brown added that so called “street triage projects” across Britain, where calls are attended by a mental health expert and a police officer, showed that in the majority of cases, police were not needed to resolve the problem.

In Lincolnshire, mental health nurses will now work in the police control room to give clinical advice to police dealing with callers.

The Met figures were obtained by the Labour party under freedom of information legislation. The full figures show that in the 12 months up to 20 July 2017, the Met received 115,000 calls flagged up on its systems as regarding mental health, up 33% on the volume of calls received in 2011-12.

Louise Haigh, the shadow police minister, said: “The dismantling of vital early intervention services forces those with mental health issues on to lengthy waiting lists.

“In desperation or in crisis, they will turn to the police, who are acting as the service of last resort, a role they are wholly unequipped for.

“While facing a savage cut in numbers, the police are increasingly being asked to pick up the pieces of a scandalous lack of mental health provision. Incidents involving mental health are at record highs as police resilience reaches rock bottom.

“The result is genuinely frightening and these figures should act as a wake-up call for the government.”

A Department of Health spokesperson said: “Everyone should be able to access the mental health support they need. We have made major improvements in recent years, including setting up the first ever access and waiting standards for mental health and increasing mental health spending year on year to a record £11.6 billion in 2016/17.