A scam offering discounted Snapper bus cards is circulating on social media.
In a post on Wednesday Metlink said it was aware of the scam.
"We are aware of scams circulating Facebook offering discounted Snapper cards in order to receive "free" travel," it said in the post.
"Please do not click on any links and DO NOT provide any personal or financial information including your password, credit card or bank account details. If you have filled in your personal details and money has been taken out of your account please make a report to New Zealand Police on 105," it said.
Snapper said it first became aware of the scam on Wednesday.
"We have been contacted by 5 customers who made us aware that the scam was circulating and to query if it is legitimate. We thank them for their vigilance. We have no reports of any customer engaging with this scam," a spokesperson for Snapper said.
"We continue to advise our customers to be cautious and to exercise their judgement - if an offer sounds too good to be true it needs to be verified.
"Only Snapper or Metlink will advise of any promotional offers and customers should only purchase Snapper cards through Snapper or authorised retailers as published on snapper.co.nz," they said.
Snapper said it had reported the scam to police, Cert NZ and Netsafe.