Jacinda Ardern says she was only told this afternoon, in response to media enquiries, there was a 15-year-old boy on last week's deportation flight from Australia.
It's just one of several flights carrying so-called 501s back to New Zealand, but hit headlines after senior Australian minister Peter Dutton said it was "taking out the trash".
A news crew was also given all access and fired questions at the deportees on the tarmac.
Speaking to reporters this afternoon, Ms Ardern said she was seeking more detail, but would expect Australia to let officials know if a minor was involved.
