National claims mental health nurses have been axed from Counties Manukau police station.
The initiative, which saw nurses placed in the watch-house, was linked to a reduced risk of harm and efficient referrals.
National's police spokesperson Brett Hudson says the roles have now been incorporated into a separate unit which is not based in the police cells.
"It's extremely disappointing and in fact dangerous, we would argue, for the DHB and police to agree between them to take those nurses out."
The programme, which saw two fulltime nurses working in cells, became business as usual in 2014.
"Being based elsewhere they can respond, but they can only respond with some sort of significant delay," said Hudson.
"Mental health issues can’t be scheduled, and you never know when someone will be brought in who needs immediate help. The absence of those watch house nurses will not only place the sufferer at greater risk, it could also put the police and wider public in danger."
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Police Minister Stuart Nash has been approached for comment.
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