The Prime Minister has made a belated pitch to Maori to support his flag referendum.

John Key first revealed plans to change the flag ahead of Waitangi Day last year, setting the wheels in motion for a two-step referendum.

Today he's urging Maori to get involved.

"If we choose a new flag, it will serve us in times of celebration and remembrance, like Waitangi Day," he said.

"It's a day when we draw confidence for our future from the sense of our past."

In his speech, Mr Key has compared the flag referendum to an 1834 vote by Maori at Waitangi to choose their own flag from three options.

John Key says the process will take longer than those few minutes but he hopes Maori will be as closely involved this time as they were back then.