Police cells should no longer be specifically included on an approved list of "places of safety" where the mentally ill can be held while awaiting assessment, MPs said.
But they were criticised by representatives of rank and file officers for failing to push for an outright ban on their use even when suitable medical facilities are unavailable.
A report by the Commons home affairs committee was highly critical of the lack of provision by "too many" local NHS commissioning bodies of properly staffed, round-the-clock specialist alternatives.
The "de facto" use of police cells was taking the pressure off health chiefs to act, putting undue pressure on inadequately trained police officers and draining vital crime-fighting resources.
A review of mental health laws led the Home Secretary to announce in December that teenagers with mental health problems would no longer be held in police cells in England and Wales and adults only in cases of extreme behaviour.
The maximum length of detention of someone in mental distress should also be cut from 72 to 24 hours, it said.
The committee backed the changes but cautioned that they should be implemented immediately by whatever government was in power after May's general election.
It also said cells should no longer be specifically listed as a legitimate "place of safety".
Doug Campbell, mental health lead for the Police Federation of England and Wales, said however that it wanted to see an end to any use of cells for the purpose, whatever the circumstances.
"Police cells are no place for the mentally ill and police officers are not the right people to look after those with mental health problems," he said.
"We have been saying for years that this is an issue for the National Health Service and we are pleased that the home affairs select committee has reinforced this view.
"We are concerned, however, that the report has backed legislative proposals by the Home Office and Department of Health that those aged 18 and over who are in mental health crisis can go to police cells for a maximum of 24 hours in exceptional circumstances.
"A mental health crisis is a medical emergency, whether a person is 17, 18, 30 or 65 and the health agencies must give them appropriate treatment rather than handing their care over to the police service.
"The Government and health service should put more effort into protecting patients and remove the pressure on an already overstretched police service to deal with the failings of the provision of mental health services for patients in crisis."
Committee chair Keith Vaz said it was a scandal that more than 6,000 people a year – including 236 children – were still being held in police cells under mental health laws.
"These people are not criminals, they are ill and often are experiencing a great deal of trauma," he said.
"The cost to policing budgets of police officers in custody suites having to deal with mentally ill people is huge.
"This puts enormous pressure on officers who are not suitably trained and is the starting point for those that are mentally ill to enter the criminal justice system. Many begin a journey which will eventually end in prison."
Care and Support Minister Norman Lamb said: "It's essential that anyone experiencing a mental health crisis gets urgent, compassionate care in the right environment. I've been very clear that I want to ban the use of police cells for under-18s who need mental health care, and (they) should only be used for adults in exceptional circumstances – we are working to make this the reality.
"We've already taken action through the crisis care concordat to get NHS, police and other services working together to improve crisis care and help end the use of police cells. Every area in the country has signed up to the concordat and nationally the use of police cells has already reduced by 24 per cent this year, but we will continue to push for further progress."
Home Secretary Theresa May said: "I welcome the support the Home Affairs Select Committee has given to the important steps this Government is already taking to vastly improve the police's response to people experiencing mental health problems and crises.
"I have always been clear that people experiencing a mental health crisis should receive care and support rather than being held in a police cell.
"The joint Home Office and Department for Health review of police powers under the Mental Health Act committed to ending the practice of police cells being used to hold under-18s in police cells and we are looking at amending legislation accordingly.
"Our reforms are already bearing fruit. Nationally the use of police cells for children and adults reduced by 22% last year compared with 2012/13 and in areas where we have piloted street triage schemes, the number of people being detained under the Mental Health Act has fallen by an average of 25%.
"However, the Government recognises that there is more work still to be done and we will consider in more detail the full list of recommendations contained in this report."
Juliet Lyon, director of the Prison Reform Trust, welcomed the report, saying: "By ensuring that people get the mental healthcare many desperately need, you avoid the harm caused by locking them in a bleak police or prison cell and the damage done to those hard-working staff who have to turn the key."
![Mentally ill should no longer be held in police cells, say MPs]( "Mentally ill should no longer be held in police cells, say MPs")
