Protestors have no scruples about targeting busy roads and jamming major highways tomorrow

Te Pati Maori is urging supporters to demonstrate against what it calls the Government's assault on tangata whenua and the Treaty of Waitangi.

The party says they expect to gridlock the main highways heading into Auckland's city centre, likely causing millions of dollars in lost productivity.

Te Runanga o Ngai Te Rangi Iwi Trust's Paora Stanley says they could do it in the middle of the night - but no one would listen.

He says they'll work with police to keep everyone safe - and are simply exercising their democratic right to protest.