New Zealand's High Commissioner to Fiji, Michael Green, has been expelled by the interim regime.
This has been announced by New Zealand's Foreign Minister, Winston Peters, who says Fiji can expect a strong reaction from New Zealand.
Mr Peters says he will now review all aspects of the bilateral relationship after the interim regime declared Mr Green persona non grata.
"The New Zealand government deplores this action. Expelling diplomats is not the way for neighbours to conduct their relationships. Mike Green is a highly respected senior diplomat of over 30 years standing and a man of great integrity. He enjoys the full confidence of our government and we are not aware of any activities he has undertaken that justifies Fiji's actions."
Mr Green has been speaking out publicly about the coup in December but Mr Peters says he was saying no more than the New Zealand government position.
He says declaring a high commissioner persona non grata is one step below breaking relations and is warning Fiji there will be consequences.
There will be undoubted consequences for Fiji as this action will be viewed very seriously, not only by us, but by Fiji's other international partners, including Pacific Island nations, Australia, United States and the European Union. I have been in contact with the interim government in Fiji in an effort to work the issue through and to urge them to reflect further. Unfortunately, it seems they are going ahead with this completely unjustifiable action. We will now consider our actions and the regime can expect a strong reaction.
Mr Peters says he's puzzled by Fiji's timing, given New Zealand had acknowledged the recent lifting of emergency regulations as a positive step.
Mr Green was a member of the joint working group set up by the Pacific Islands Forum and the interim administration which was put together to work out how the country could be returned to democracy as soon as possible.
That group appointed a team which assessed that Fiji could hold elections as soon as November next year despite the interim administration that it would not be able to do so before 2010.
Fiji's interim Foreign minister, military representatives and the interim prime minister's secretary were all unavailable to comment.