The number of batteries being removed from the checked luggage of airline travellers has soared - increasing five-fold in a year.
Civil Aviation Authority (CAA) figures show 5796 batteries were seized in New Zealand in 2016.
Last year, the number jumped to nearly 33,000.
CAA manager Karen Urwin said most are lithium batteries in electronic devices, which are a dangerous good and must be carried in hand-luggage.
"They can overheat so if it's in your carry on luggage we can immediately see if there's a problem - smoke comes out of your handbag or out of the seat in front of you and you can deal with it.
"But when it's locked away down in the hold, it's a lot more dangerous," she said.
Ms Urwin said people should check online before packing, to find out which items cannot be checked in.