Euthanasia advocate Patsy McGrath had her store-bought helium balloon kit seized by Nelson police on the same day as a Wellington woman was arrested on charges of importing a class C drug.

Two elderly Wellington women with suicide drugs have been pounced on by police, who are conducting a national operation thought to be targeting a euthanasia group.

Police have confirmed a Lower Hutt woman was arrested and faces two charges of importing a class C drug as part of an "ongoing investigation".

It is understood a second elderly woman was also involved in the October 7 raid, part of what police are calling Operation Painter, and that one of the women spent the night in a police cell.

Exit International director Philip Nitschke says police are cracking down on his euthanasia group's elderly members.

Exit International director Philip Nitschke said police raided several elderly members of his group as part of a world-first clampdown on his organisation.

READ MORE:

* Police seize voluntary euthanasia advocate's helium balloon kit

* Thousands of older people exploring 'rational suicide': Nitschke

* Families smuggling lethal drugs into Oz hospitals so loved ones can die: Nitschke

* Fighting for the right to die - Matt Vickers campaigns in the name of his late wife Lecretia Seales

​"It is ludicrous to try to argue that these raids are in the best interest of the Exit members raided," he said.

"They are clearly designed to intimidate and frighten, and send a message that the elderly are not to have control over their own death."

Police have repeatedly refused to say what the drug was, the age of the arrested woman, or when she would appear in court. They have also refused to comment on claims they had got hold of Exit's membership list and were working their way through it.

Nitschke said the police operation was a "proactive" attack on euthanasia on a scale not seen in any country in which Exit operated, and the Lower Hutt case was the first charge of its kind in New Zealand.

FAIRFAX NZ Supporters of voluntary euthanasia at the presentation of a petition to Parliament in June.

"It is a bit of a series of attacks on Exit. This is quite a unique development."

He said it appeared a police task force had "infiltrated" Exit, whose members have an average age of 75, as they cracked down on people wanting the option of dying on their own terms.

Pentobarbital, which has the trade name Nembutal and is the euthanasia drug of choice for Exit International, cannot be legally obtained in New Zealand, but can be imported from overseas.

STUFF Euthanasia advocate Lesley Martin in 2006. She claims Nitschke is a "rogue and a maverick", who is undermining the campaign to legalise euthanasia.

Under the Misuse of Drugs Act, it is classified as a class C drug, and the maximum penalty for importation is eight years in jail. That compares with penalties of about 10 years in jail for anyone assisting another in suicide.

Nitschke was not aware of any previous cases of New Zealanders being charged for importing Nembutal. During the past 20 years, only four Australians had been charged.

Each Australian case had resulted in a fine, but no conviction.

"STUFF THE LAW"

Euthanasia advocate Lesley Martin, who served half a 15-month jail sentence for helping her terminally ill mother to die, said Nitschke was a "rogue and a maverick", who was undermining the campaign to legalise euthanasia.

She claimed Exit operated at the fringes of the law, and said there was a divide between Exit and the Voluntary Euthanasia Society (VES).

"[Exit] just say stuff the law, we will provide the method and means for people to do it themselves ...

"It's just the same old, same old – he's still not helping the overall situation of legitimising and legalising euthanasia."

VES spokesman Dave Barber was at pains to distance the society from Exit, but was surprised at the police raids.

"A parliamentary committee is currently holding a public inquiry into the whole issue of assisted dying," he said.

Surveys consistently showed between 60 and 70 per cent of New Zealanders favoured a change in the law, and he believed police would "perhaps be better advised to await the outcome of the inquiry".

On the same day as the Wellington raids, Nelson police turned up at the door of 76-year-old voluntary euthanasia advocate Patsy McGrath with a warrant to seize her store-bought helium balloon kit, which could be used for suicide.

She handed over the kit, but said later she was angered by the "frighteningly wide" powers police had to intrude on her privacy.

Customs does not have specific figures for Nembutal seizures. In 2015 it made 1458 seizures of class C drugs, which included Nembutal.