Around the night of Sunday, January 30, offenders sawed halfway through the pole, cut two of the supporting cables and sprayed the pole, a memorial stone and signs with graffiti.
The same purple paint was used in a graffiti attack in November when slogans about a supposed New World Order and "fredom" (sic) were daubed on the pole.
The top of Maiki Hill has been fenced off for safety until permanent repairs can be carried out.
The flagpole was erected in 1858 by Maihi Kawiti, son of the Ngāti Hine warrior chief Te Ruki Kawiti.
The attack upset local hapū who for the first time in decades were unable to hold a flag-raising ceremony at dawn on Waitangi Day.