The historic flagpole on Te Maiki Hill in Russell has been damaged and the surrounding area has been graffitied.
The flagpole at Te Maiki Hill. Photo: Wikimedia Commons / Noel Jones
Police are now investigating the incident at the significant site.
The damaged is believed to have happened sometime between Sunday 30 January and Monday 31 January, police say.
"This area is now unsafe, and has been fenced off while the Department of Conservation works to restore the structure and its surrounds, so it can be safe and enjoyable for the public once more," police said.
Anyone with information is urged to call 105 and quote file number 220202/8881.