Auckland, New Zealand - Pineapple candy dished out by a New Zealand charity have tested positive for potentially lethal amounts of methamphetamine, police said Wednesday, sparking an urgent race to remove it from the streets.

A child, a teenager and a charity worker have already been taken to hospital after they tasted the candies.

Although none are seriously ill, police have launched a criminal investigation and are now trying to track down up to 400 other people who may have received the candy.

"We need to round these up as quickly as we can," said Detective Inspector Glenn Baldwin, adding that 16 of the candies had been found so far.

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Police suggested the drugs might have been packaged under the Rinda brand by traffickers or dealers to evade detection.

They are then believed to have been donated to anti-poverty charity the Auckland City Mission, which inadvertently distributed them via a food bank.

"Drug importation is complex, and organised criminal groups use a range of measures and techniques to try and evade enforcement agencies, not only in New Zealand, but around the world," Baldwin said.

A child and a teenager were taken to hospital after tasting the candy and spitting them out. Both are doing well, Baldwin added.

A charity worker was also treated for symptoms consistent with methamphetamine, but later discharged.

The New Zealand Drug Foundation said a test sample of an innocuous-looking piece of white candy in a bright yellow wrapper indicated it contained methamphetamine.

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Foundation spokeswoman Sarah Helm said the tested candy contained approximately three grams of meth – hundreds of times greater than the common dose taken by users.

"Swallowing that much methamphetamine is extremely dangerous and could result in death."

Helm urged people who had received confectionaries from the Auckland charity not to consume them.

"We don't know how widespread it is."

The Auckland City Mission's Helen Robinson said the organization was "devastated" by the news.

She believes as many as 400 people could have received the affected candy in a food package. Eight separate families had so far been affected, she said, including one instance where a parent gave one of the candies to her child, who immediately spat it out.

Robinson said she had been told the contaminated sweets tasted "acrid and revolting."

"You could have only a very small touch or lick of the substance and still be deeply affected," she warned.

Meth can cause chest pain, racing heart, seizures, delirium, and loss of consciousness, the drug foundation warned.