AUCKLAND, July - The school's parent-run organisation, Friends of Drury School, ran the annual possum hunt fundraiser this month.
But Waikato animal rights activist Lynley Tulloch attended the fundraiser and claims young possums were taken from their mother's pouches and drowned.
She has started an online petition calling for school possum hunts to be banned. It had more than 6000 signatories by Sunday afternoon.
Drury School's board of trustees responded by posting a statement in which it said the SPCA had advised it "the method used in putting down joeys is not considered humane".
"The school has learnt from this and we will be working with the SPCA to ensure that all animal welfare requirements are met in future so that the focus is returned to the commendable intent of the fundraising itself," the statement said.
Drury School said it was proud of its rural heritage with the annual possum hunt raising money through the sale of dead animals to a fur buyer.
While the hunters are required to remove and humanely dispose of any joeys, the animal's pouches also need to be checked again at weigh in, it said.
"Any joeys found dead or alive were removed from the carcass as the fur buyer doesn't take any joeys," the school said.
"They were then put down in a manner that was believed to be lawful."
Tulloch intends to present her petition to Education Minister Nikki Kaye.
"Possum hunting events demonstrate an absolute lack of conscience," she wrote.
"This is made more disturbing as it involves young children who are still in the process of developing their personal values. In an educational context, this is completely inappropriate."
Possums are pests in New Zealand. The Department of Conservation says they are one of the greatest threats to the natural environment.
Possums compete with native birds for habitat and for food such as insects and berries. They also disturb nesting birds and eat their eggs and chicks.