Prime Minister John Key has backed away from his comments about euthanasia, saying his language on the sensitive issue was "a bit sloppy".

Key last week said "there is a lot of euthanasia that effectively happens in our hospitals".

The comment angered doctors who said euthanasia was never practised as it was the deliberate ending of life, and was illegal and unethical.

The suggestion could seriously damage the trust people had in hospital care of the terminally ill, doctors said.

Capital & Coast District Health Board head of palliative care Jonathan Adler said switching off a life support machine and allowing someone to die of natural causes was not euthanasia.

Key today said his comments were made on talkback radio.

"It was in the context of a wider discussion about a scenario where I think I am saying the same thing as those doctors," he told Radio Live.

"They use specific and arguably accurate legal or medical definitions and I was using a bit of a general term."

The prime minister said he was not suggesting doctors were doing anything illegal.

"I acknowledge when a family makes a decision to switch off a life support unit, if they do, that that is not euthanasia as it is legally defined but I am just saying the practical implication of that is someone passes away."

Key said he accepted the doctors' point. "I was probably a bit sloppy in my language."

Labour MP Maryan Street has an "End of Life Choice" Bill in the private member's ballot but it must be drawn before the issue is debated by Parliament.

Key said his comments were a way of him explaining why he might vote for such a law.

"I think if you are terminally ill and have a couple of weeks to live, personally, I don't like seeing people go through a lot of pain."

- © Fairfax NZ News