UPDATED 1.33pm: The Prime Minister is unfazed by a second meeting on changing the flag, where only a handful of people turned up.

Two public meetings this month haven't attracted much interest, with five people at one, and 14 at the other.

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Two public meetings this month haven't attracted much interest, with five people at one, and 14 at the other.

But John Key says, just because people don't want to come to a public meeting, doesn't mean they're not interested.

"Once we get to the point where there are four flags for people to vote on the first referendum, and then a run off between that and the current New Zealand flag, I'd probably bet my bottom dollar there'll be considerable debate and discussion."

The public consultation process is estimated to cost $6.7 million, with the total cost of the referendum expected to come to $25.7 million. 

A further 22 public meetings have been scheduled with a first referendum to choose a design planned for later this year. Over 2300 flag design submissions have been received.

If the flag is changed, the government estimates it will cost $2.66 million to replace flags on government buildings, facilities and defence uniforms.