The number of mentally ill people who have been killed through euthanasia in the Netherlands has trebled in a single year, according to new figures.

The Daily Mail reports that in 2012, 14 people with “severe psychiatric problems” were killed by lethal injection, a figure that rose to 42 in 2013.

There had also been a 15 percent overall rise in assisted dying over the past year, with the number of cases increasing from 4,188 to 4,829.

Deaths from euthanasia have risen by a total of 151 percent in a period of just seven years, with most cases involving cancer sufferers. However, there were also 97 people who were killed by their doctors because they had dementia.

The figures do not include “terminal sedation”, where the patient is sedated and then has food and fluids withdrawn. If they did, however, euthanasia would account for one in eight of all deaths in the Netherlands.

Dr Peter Saunders of the Christian Medical Fellowship told the Daily Mail that euthanasia in the Netherlands is “way out of control”, saying that it proves that assisted dying is impossible to regulate.

“The House of Lords calculated in 2005 that with a Dutch-type law in Britain we would be seeing over 13,000 cases of euthanasia per year,” he added.

“On the basis of how Dutch euthanasia deaths have risen since this may prove to be a gross underestimate.

“What we are seeing in the Netherlands is ‘incremental extension’, the steady intentional escalation of numbers with a gradual widening of the categories of patients to be included.

“The lessons are clear. Once you relax the law on euthanasia or assisted suicide steady extension will follow as night follows day.”

In Britain, a bill that would legalise assisted dying received its second reading in the House of Lords in July and will continue to the next legislative stage in November.

Earlier this year, Dutch regulator Theo Boer told the British Parliament “Don’t go there” when asked about the British proposals.