The company said it had kept Patuharakeke and Ngatiwai up to date about its plans to sell the combined 166ha of land.
Ms Kapua said the hapu might ask for urgent court action to block the sale until its claim is resolved.
"Part of the purpose of the memorials is to give people notice that there is an issue with that land. But once it goes into private ownership - and the (Waitangi) Tribunal won't make an order to return private land - it will be alienated forever and Patuharakeke will not have the money to afford to buy it at whatever the market value is," she said. "At the moment it's still got the Crown's hands over it so we'd like to see OTS take this land and land bank it to then be offered back (to the hapu) as part of its Treaty of Waitangi settlement." She said the hapu would use the land to establish an economic base and help to provide for hapu members.
"Almost all of Patuharakeke's land has been taken and most is now lost. That has a deeply psychological effect on them and this really is an issue of fairness." The OTS did not respond to the hapu's concerns by edition time.
The sale is being marketed by Colliers International which says of the sites:
Develop or hold for future opportunities. Mix of coastal property and farmland, one tenanted house - existing holding income from grazing on parts. On main route to Marsden Pt refinery and Northland Port.
This is your chance to secure a large Business 2 and 4 zoned land holding spread over multiple titles or select one or more of the individual parcels. Land bank, farm, or develop now to capitalise on Marsden Pt's growth.
The land includes the 40ha (approx) former Marsden power station site, now cleared of improvements, and directly adjoining beach front, over a DoC reserve, of over 600m.
Potential sea water intake rights available if required.
The sales pitch does not mention the Section 27b memorials on the sites.