A New Zealand government official has asked for an explanation of a Dublin taxi fare charged to Prime Minister John Key's credit card - despite Key being 18,000km from the city at the time.

The New Zealand Department of Internal Affairs is looking into the €52 (NZ$87) charge to the PM's credit card. Mr Key (pictured) has not visited Ireland in two years.

The New Zealand Herald reports a spokeswoman said the credit card details belonged to one of Mr Key's staffers and were fraudulently used to purchase a cab fare in Dublin without the Prime Minister's knowledge.

She told the NZ Herald: "The card holder has not been to Ireland for almost two years and has no knowledge of the charge. It was most certainly not authorised by the cardholder or anybody else in this organisation."

The bank has reimbursed the charge.