Wellington authorities are bracing for big crowds, as up to 30,000 people are expected to join the Hīkoi mō te Tiriti marching on Parliament tomorrow.

Marchers have walked the length of the North Island in opposition of ACT's Treaty Principles Bill - and the nine-day journey is set to come to an end.

Newstalk ZB senior political correspondent Barry Soper says Police Minister Mark Mitchell has confirmed there are preparations in place ahead of tomorrow's event. 

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