Labour says the Justice Select Committee is expected to report back on the Treaty Principles Bill on Friday - more than a month ahead of time.

Parliament set down a deadline of the 14 May, and a Cabinet minute shows the committee was set to consider it until 16 May.

But Labour's Justice spokesperson Duncan Webb - who had previously sought an extension to avoid thousands of public submissions being excluded - now says the timeline has been moved up.

"The committee finished more than a month ahead of the 14 May deadline set by Parliament with the report expected to be presented and available tomorrow (Friday)," he said.

Webb said the Committee had "rammed it through with outrageous haste" and the early report would exclude those thousands of submissions.

"With government members rushing to report the bill back early, the process is exposed for what it really is - a sham," he said.

"This shows utter contempt for the many New Zealanders who took the time to submit and whose views are now missing from the record.

"This is an appalling lack of process on a hugely consequential bill."

Prime Minister Christopher Luxon has previously said the record number of submissions overwhelmed the committee, and that Labour was playing politics.

He this week doubled down on allowing the submissions to be excluded, despite warnings from legal scholars the move would set a precedent that could erode democratic participation.

-RNZ