More than 35,000 people have gathered as the Hīkoi mō te Tiriti overflows from Parliament's grounds and onto nearby Wellington streets.

Eru Kapa-Kingi told the crowd "Māori nation has been born" today and that 'Te Tiriti is forever'.

ACT leader David Seymour was met with chants of "Kill the bill, kill the bill" when he walked out of the Beehive for a brief appearance at Parliament's forecourt, before waving to the crowd and returning into the building.

The Treaty Principles Bill architect, Seymour, says he supports the right to protest, but thinks participants are misguided and have a range of different grievances.

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