Officials have been left "utterly disappointed" after three mountain bike tracks were illegally carved into Mt Victoria in the Auckland.
The tracks, discovered last Friday, have caused extensive damage to the mountain, which is a protected site of a historic Māori pā settlement.
Nick Turoa, Tūpuna Maunga Authority operations manager, said the tracks appeared to have been carved deliberately for mountain biking.
"The configuration of the tracks and the excavation of dirt to construct ramps and berms on downward slopes suggest mountain bikers have undertaken these illegal activities," he said.
"It is utterly disappointing that there are people who would desecrate this ancestral maunga and taonga with complete disregard to the history and cultural and archaeological significance."
The tracks are 12m, 20m and 25m in length, are up to 1m wide and up to 40cm deep in parts.
At one section the path traverses a historic pā terrace and there is also evidence of disturbed midden, or ancient shell deposits, dating to the pā site.
Given the historic significance of Mt Victoria, also known as Takarunga, any illegal modification is prosecutable under the Reserves Act 1977 and the Heritage New Zealand Pouhere Taonga Act 2014.
Turoa said the damage has been reported to Heritage New Zealand.
"Tūpuna Maunga Authority staff and contractors will be closely monitoring all activity occurring on Takarunga, and in particular mountain biking," he said.
"Visitors to the maunga are welcome to cycle on sealed road surfaces but off-road biking is strictly prohibited on all areas of the maunga.
"We have a zero-tolerance of unauthorised digging on the maunga and anyone found responsible for such activity will be prosecuted.
"We are seeking information from anyone who might know something about this."
• Anyone with information about these tracks is encouraged to contact the Tūpuna Maunga Authority at MaungaAuthority@aklc.govt.nz or 09 301 0101.
Similar damage occurred at another Auckland maunga and historic pā site, Ōtāhuhu / Mt Richmond, in October 2018.
A 20-metre track suspected to have been dug out was sliced through the ancient archaeological site.