An Auckland Local Board chair is concerned children are using large nitrous oxide canisters

The gas is sold legally for whipped cream use but can also be used illegally as a psychoactive substance.

The canisters are 3.3 litres, about the same as 300 smaller canisters - known as nangs.

Manurewa Local Board Chair Matt Winiata says after seeing one he's spotted them littered across streets in his local area.

He says he saw nine more during a ten minute drive.