A whale bone patu has gone missing from the Rotorua Lakes Council chamber.
The council discovered last week the short-handled club was not in its display case.
Officials carried out a search, checked security footage and contacted anyone who may have removed it for safekeeping, but the patu still has not been found.
Rotorua mayor Steve Chadwick said the patu was kept in a perspex display case on a plinth in the chamber. The case was not locked, though the chamber was.
"We've looked at the video footage and there's no evidence of anybody coming in, so we don't know how it disappeared, but we're pleading - please, just bring it back."
The last confirmed sighting of it was on 15 December, at the last council meeting.
"It has been difficult having to tell our members, whānau, iwi and the patu's carver that it has disappeared, given its purpose is to hold the life force or spiritual essence of our partnership with council. It also recognised the tireless efforts by the late Mauriora Kingi, who was instrumental in the forming of this union and to whom it's dedicated."
The patu was gifted to the council in December 2015 and recognises the partnership between the council and Te Tatau o Te Arawa.
Te Tatau o Te Arawa chair Te Taru White was hopeful it would be returned.
"If the person has some sense or conscience, we're hopeful and if it comes back, through whatever source, I know that we're all prepared to give an amnesty in this space, because the most important thing is that we get it back," he said.
Since being gifted to council it has been used several times during official ceremonies, such as pōwhiri.
Mr White said it was a special taonga.
"Its value is not monetary but it has huge spiritual and cultural significance. It was a gift to the council and the wider community as a symbol of partnership, hope and prosperity. This taonga has no worth to whoever has taken it and we plead to their conscience for its return."
Police have been informed.