New Zealanders have voted overwhelmingly to legalise euthanasia, preliminary referendum results released Friday showed, with another vote on allowing recreational cannabis appearing set to fail.

The dual referendums were held on October 17, alongside the general election that returned Prime Minister Jacinda Ardern to power with a landslide majority.

Preliminary figures showed 65.2 percent of voters supported euthanasia, with 33.8 against, while 53.1 percent opposed legalising recreational marijuana, compared to 46.1 in favour.

The initial figures do not include special votes -- including ballots cast overseas -- which account for almost 20 percent of the total and could still see the cannabis vote go either way.

However, the overwhelming support for euthanasia means the measure will pass, regardless of how the special votes are divided, when final figures are released next Friday.

The result of the euthanasia vote is binding, while the cannabis one is not.

Legislation allowing medically assisted death passed through parliament last year but lawmakers delayed implementing it until the public had its say through a referendum.

Under the law, a mentally sound adult who has a terminal illness likely to kill them within six months and is experiencing "unbearable suffering" can request a fatal dose of medication.

The request needs to be signed off by the patient's physician and an independent doctor, with a psychiatrist called in if either has doubts about the person's ability to make an informed decision.

Justice Minister Andrew Little said it would come into effect in November next year.

Ardern supported the right-to-die bill, saying last year she reluctantly agreed to the referendum because it was the only way to advance the legislation.

She was coy during the election campaign about her stance on recreational cannabis, although the 40-year-old did admit to smoking marijuana "a long time ago".

Ardern's office confirmed Friday she had voted "yes" in both referendums.

She "will progress any legislation in line with the will of the people following the release of the final results next week", a spokeswoman for Ardern said.

Under the proposed cannabis law, anyone aged over 20 could buy up to 14 grams (half an ounce) a day, and households could each grow up to four plants.

ecreational cannabis will remain illegal if the "no" vote is still over 50 percent next Friday.