Within the past four years, 122 people have died unexpectedly while being treated for mental illness in the capital region, according to a study commissioned by the City Council after three patients admitted to the psychiatric wards at two different Greater Copenhagen hospitals died while under the care of hospital personnel.

In January, two patients died while confined to a secured ward at the psychiatric centre of Copenhagen's Bispebjerg hospital. The third patient died in February while being treated at a ward at Mental Health Centre North Zealand in Hillerød.

All three of the deceased patients received a combination of anti-psychotic and sedative drugs. The national board of health does not recommend such a drug protocol due to the risk of serious side effects. All three patients had taken methadone, a powerful sedative and morphine-like drug. A combination of other medications being taken on top of the methadone is thought to be the cause of the deaths. An autopsy report revealed that one of the patients had a total of five kinds of psychotropic drugs in his blood when he died.

The new figures include patients hospitalized in both open and secured wards and those who were receiving outpatient treatment at an area psychiatric centre. The report is unclear on how many of the deaths were the direct result of treatment that the patient was receiving, and 81 of the 122 were listed as suicides.

Council member Charlotte Fischer (Radikale) said that she will be asking the person in charge of capital region's hospitals to clarify the reasons for the death toll.

"I think that 122 deaths is a very high figure,” she told Politiken newspaper. “We need to be better at preventing these unexpected deaths among patients, whether hospitalized or not.”

Fisher wants answers on how many deaths were related to treatment and if some of the suicides could have been prevented.

"We need to delve into these patients' history to find out if there is anything we need to do differently in the future,” she said.