The practice of sending mentally ill people long distances for treatment should end, a commission has said, as experts branded some services "potentially dangerous".
Around 500 mentally ill people every month are estimated to travel over 50km (over 30 miles) to be admitted to hospitals far from their own homes.
These long-distance admissions are mainly due to difficulties in finding acute inpatient beds or suitable alternative services in the area where they live.
A new independent commission led by Lord Nigel Crisp and supported by the Royal College of Psychiatrists says thousands of people in England each year are "travelling unacceptably long distances for acute admissions" and calls for the practice to end by October 2017.
A report from the commission said: "Out of area treatments cause problems for patients and for their families and carers. Geographical separation from a patient's support networks can leave them feeling isolated and delay recovery.
"Moreover, mental health personnel from the patients' home area have difficulties in visiting them with the result that they may well spend longer as inpatients than they would have done if admitted locally."
The commission also said there were major problems in people being able to access acute care, partly due to a lack of funding and inadequate staffing.
It said: "Access to acute care for severely ill adult mental health patients is inadequate nationally and, in some cases, potentially dangerous."
There are also issues with suitable community alternatives to admitting people to hospital.
"Members of the commission were told that significant numbers of patients were admitted because of a lack of alternatives and many also had their discharges delayed," the report said.
In 2013/14 1.7 million people in England used mental health services, with 105,270 admitted to hospital.
As of 2011/12, NHS spend on adult mental health services in England was £6.63 billion. There are also the indirect costs of mental illness, including time lost from work or education.
The commission wants a new four-hour wait target to be introduced for admission or acceptance for home-based treatment following assessment for acute mental illness.
Lord Crisp said: "It is time to end the difference in standards between mental and physical illnesses. People with severe mental illnesses need to be able to find care just as quickly as people suffering from physical illnesses - and they shouldn't have to travel long distances to do so."
Professor Sir Simon Wessely, president of the Royal College of Psychiatrists, said: "Everyone agrees that it is a scandal that patients with serious mental disorders who need admission can end up being sent anywhere from Cornwall to Cumbria in a search for a bed. And yet it continues.
"In particular we stand alongside Lord Crisp in asking that there is a new pledge for a maximum four hour wait for admission or home treatment by 2017, and that the unacceptable practice of sending seriously sick patients around the country is ended by the same date. If we were talking strokes, heart attacks or cancer, we wouldn't even have to ask."
Brian Dow, director of external affairs at Rethink Mental Illness, said: "If you have a physical health emergency you expect to be treated quickly, not sent miles from home.
"So why is this acceptable if you have a mental health emergency? Mental health remains a neglected service. The Government has promised to invest an £600 million during this Parliament which is incredibly welcome, but to put that into context, almost £600 million was cut from mental health services in the last Parliament, so essentially it's filling up what was previously drained out."
Marjorie Wallace, chief executive of the mental health charity Sane, said: "The fundamental cause of the failings, neglect and risks taken with the lives of psychiatric patients is the relentless agenda adopted by successive governments to close down psychiatric beds and units and replace them with community teams.
"Patients are also being held in police cells, or shunted hundreds of miles across the country. In one case known to us, the parents of one 18-year-old girl have travelled 25,000 miles over the last two years to visit her in four different psychiatric units because there is no psychiatric bed in Cornwall.
"The Government promised a revolution in psychiatric services last month, but no money to replace the beds already closed, nor any guarantee that the £10 million funds pledged will reach the frontline."
Mental health minister Alistair Burt said: "It's crucial that people get the mental health care they need as quickly and as close to home as possible.
"Last year, I asked NHS England to reduce unnecessary out of area treatments, and eliminate their inappropriate use. We agree that there should be standards for what people can expect from mental health treatment, and when. NHS England and others will be working on this over the coming months."