Three euthanasia cases involving women with psychiatric conditions and dementia are under investigation in the Netherlands, the Observer can reveal.

Prosecutors confirmed that the deaths, in 2017 and 2018, were being investigated for potentially breaching strict conditions in the 2002 law that allows people in the Netherlands to ask a doctor to help them die.

The confirmation comes two weeks after news organisations around the world incorrectly reported that Noa Pothoven, a 17-year-old Dutch girl with anorexia, who had been sexually abused as a child, had died through euthanasia – with even the pope tweeting that the practice was “a defeat for us all”.

Separately, in August, a Dutch doctor will be the first prosecuted for failings, in a 2016 case, in which sedatives were put in a dementia patient’s coffee and her family asked to hold her down when she struggled against the euthanasia injection.

Dutch euthanasia law requires patients to be experiencing unbearable suffering, with no prospect of improvement, and to have a voluntary, sustained wish to die; doctors must also seek a second independent opinion.

The latest report by the Dutch Regional Euthanasia Committees – which examine legal compliance in every case – shows prosecutors are investigating a doctor for failing to treat the case of a woman with “due diligence” last year. According to the report, a woman in her 70s with depression had been operated on for abdominal problems when surgeons found evidence of lung cancer. She approached her doctor, saying she was experiencing unbearable psychological suffering and wanted euthanasia. Her doctor’s colleague took on the case, but, the review committee said, failed to obtain a second opinion from an independent psychiatrist, as is required.

The two other cases, from 2017, involve a woman in her 60s with Alzheimer’s whom an independent consultant did not judge to be suffering badly enough, and another in her 80s with osteoarthritis and other problems who refused other treatment.

The investigations have raised alarm, according to Dick Bosscher of the NVVE, the organisation that campaigned for the euthanasia law. “We think doctors are holding back more, although we can’t prove it,” he said. “Last year, for the first time in years, there were fewer euthanasia cases in the Netherlands. Whether things are clear for doctors is a difficult question, as unbearable suffering is different from one person to another.”

The issue has divided doctors: last year, 450 put their names to a full-page advertisement saying they would not give a deadly injection to an incapacitated patient. One ethicist,

Berna van Baarsen, resigned from a regional euthanasia committee in protest at the growing role of advance directives for people unable to express their wishes.

Cases involving psychiatric suffering and dementia are, however, relatively rare. In 2018 there were 6,126 cases of euthanasia (compared to 6,585 in 2017): 1% involved psychiatric conditions, and 2.4% dementia. Two-thirds were requested by people with terminal cancer.

A staff member for the review committees – who did not want to be directly quoted – pointed out that a teenager with anorexia cannot simply ask for and receive euthanasia, each case is extremely nuanced, and the committees have issued detailed guidelines to doctors. In 2015, the committees reported that euthanasia accounted for 4.6% of 147,000 Dutch deaths, while 18% of people who died had palliative sedation – such as morphine – as they died.

“Euthanasia law is a constant matter of debate, and individual cases involve complex consideration,” said Axel Dees, spokesman for the health ministry, which has just launched a campaign OnAbout Palliative Care to encourage people to plan for the end of their lives. He said the government is researching a 2016 euthanasia proposal for those ineligible under current euthanasia law, but who feel their lives are “complete” – something that one member of the governing coalition, the ChristenUnie, opposes.

The debate on “complete lifers” is expected to be fierce, but pro-euthanasia campaigners say psychiatric reasons are as valid as physical ones – arguing that otherwise, people would commit suicide, as Pothoven effectively did by refusing food and drink.

Elke Swart, a spokeswoman for the End of Life Clinic – which Pothoven said refused her request for euthanasia last year – said that its focus is preserving life. “Patients say: I don’t want to die, but I cannot live,” she said. “Less than a third of euthanasia requests are granted. Most don’t fulfil the legal criteria or people see during the process – which is very intensive and can take years – reasons to stay alive. This is of course the best result.”

Swart added: “Euthanasia is the ultimate cry for mercy from someone in extreme need, and every request deserves careful consideration.”

In the UK, Samaritans can be contacted on 116 123. In Australia, the crisis support service Lifeline is on 13 11 14. In the US, the suicide prevention lifeline is 1-800-273-8255. Other international helplines can be found at www.befrienders.org