Labour's promise to extend the Working for Families tax credit to beneficiaries has been labelled a "welfare trap" by Prime Minister John Key.
The party's $2.6 billion policy to tackle child poverty includes giving beneficiary families an extra $80 a week.
That part of the policy will take six years to fully implement and cost $349 million a year by 2018.
Mr Key calls the plan a step in the wrong direction which will "trap people on welfare".
"I think the single biggest thing we can do [to tackle poverty] is actually try and get people off welfare and into work," he told Radio New Zealand.
He says Labour's policy is saying to a lot of people "You are going to be destined to a life of low income" if they did not come off welfare.
Mr Key again attacked Labour's figures, saying the party's taking "a rather schizophrenic approach" to its election pledge costings, which don't add up.
"Yesterday, they were out there saying OK, we're now going to spend what is a very, very expensive and large price tag for their children's policy.
"Everything we've ever seen from Labour is those schemes cost a hell of a lot more."
Labour leader Phil Goff on Tuesday defended the policy, which also includes extending paid parental leave from 14 to 26 weeks.
He told TVNZ's Breakfast programme Labour had worked out all the costs, and it was affordable because of the six-year phase-in period.
Mr Goff says National has its priorities wrong - giving tax cuts to the rich, instead of taking children out of poverty.
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