The Transport Agency is warning parents and caregivers after it found some online retailers are selling unsafe child restraints for cars.
Some restraints available online do not meet approved safety standards and could put children at risk in a crash, it said.
The agency said when shopping for child restraints, people should make sure the products meet New Zealand safety standards.
Any driver who has failed to ensure passengers under the age of 15 are using approved restraints could face a fine.
Child restraints should be labelled with a tick mark, an E mark that meets European standards, an S mark indicating safe use in New Zealand, and labelling that complies with United States standards, the agency said.