(AFP) - Food parcels dished out by a New Zealand charity unknowingly contained pineapple sweets laced with potentially lethal amounts of methamphetamine, police said Wednesday.

The charity Auckland City Mission raised the alarm after discovering a batch of the sweets was contaminated with the highly addictive illegal drug, police said.

"An investigation is under way and police are treating the matter as a priority given the risk to the public."

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

Foundation spokeswoman Sarah Helm said the tested sweet contained approximately three grams of meth -- up to 300 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 any confectionaries from the Auckland charity not to consume them.

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

The candy was donated anonymously by a member of the public, the charity said, in a sealed branded package.

A contaminated sweet was taken for testing when a person felt strange after starting to eat it and noticed a bitter taste.

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

Helm told Radio New Zealand that it is common for drug smugglers to hide illegal narcotics in food form.

"We suspect somebody hasn't intentionally sought to poison children. It will be up to police to determine," she added in the interview.

© Agence France-Presse