Anyone offered cheap sheep meat should be wary because it could make them ill, Northland police say.
Police are advising people to be cautious if buying meat products from individuals, because the meat may not be safe to eat.
Three sheep were stolen from a farm in Kaipara District overnight last Thursday. Police suspect the animals were taken and killed for meat.
However, the sheep were drenched with worming chemicals a week ago. The chemical can stay in the sheep's system for up to 28 days and consuming this meat may result in illness.
Anyone with information can call their police station or Crimestoppers anonymously on 0800 555 111.
