A Labour flyer personally addressed to mothers on welfare has been labelled "threatening" and prompted a complaint to the Electoral Commission.
However Labour says the pamphlet was justifiable as a response to a "negative, hard-hitting" National policy and it sourced recipients using publicly available information.
The flyer, authorised by the party's General Secretary Chris Flatt, featured a picture of a baby girl and the message "Under National, you won't be around to celebrate her first birthday".
Inside it begins: "Being pregnant is stressful enough without having to wonder if you'll lose your benefit" before listing Labour's family policies.
Hamilton mother Daniela - who didn't want to use her last name - said she was shocked to receive the flyer in the post.
"Especially when it said I wasn't going to be around. That was quite threatening," she said.
"I don't know how they knew I was a mum with a little baby. I know there might be some information open to them but I don't think they should be able to use it like that."
Daniela also forwarded the flyer to the blogger Whale Oil, saying she was upset because she felt like the letter made it sound criminal to head back to work after having a baby.
Labour campaign spokesman Grant Robertson said the letter was supposed to be hard-hitting in response to a hard-hitting policy.
"The only thing that's threatening here is the policy itself. It will force woman back out to work. We believe it's a very negative policy," he said.
Using the electoral roll to search for occupation and gender, Labour had sent the flyers to female beneficiaries, he said.
It wasn't an exact science, and Robertson apologised if some people had received the note and it didn't apply to them.
We are delighted that this awful piece of propoganda is being reported widely; it deserves to be. It is scaremongering at its worst, and to compound things, it is untrue. National's welfare reform will require parents on benefits to seek part-time work when their youngest child turns five. Beneficiaries who have subsequent children will face an expectation that they will seek part-time work when the child turns one.
That is a long way from the wording of the pamphlet; under National’s new welfare policy beneficiaries who get pregant will be forced to find work when their baby turns 1.
And Labour is taking an absolute caning on the Stuff site; scroll your way down through almost 200 comments and you'll see some real doozies!