Debate's been fierce as MPs passed the second reading of legislation enabling referenda on the future of the country's flag.

Opposition parties are against the move - Labour MP Chris Hipkins is critical of the way the process has been run.

"Why are they willing to spend tens of millions on a referendum process, but they can't spare more than 10 minutes for the RSA to give their views at the Select Committee?"

But National MP Chris Bishop says Labour's opposition is based on spite.

"That is the simple reality of it. The Labour Party has this vainglorious view of itself, that it is the party that does nationhood."

The Bill passed 63 votes to 58.