ACT Party leader David Seymour says there's "no rhyme nor reason" for keeping Auckland under alert level 3 on Saturday.
Seymour says if the Government was confident with its contact tracing and self-isolation system, then Aucklanders should have more freedom.
Auckland will shift to alert level 2 at 6am on Sunday and the rest of the country to alert level 1, Prime Minister Jacinda Ardern announced on Friday.
"There is no rhyme nor reason for spending an additional day at alert level 3 in Auckland but the cost is estimated at $45 million," Seymour said on Friday.
"Hard-working business owners will lose another day of profitability for no clear reason, and the Prime Minister is still not telling the truth.
"At the same press conference that the Prime Minister said that she would start telling us the plan for COVID 'over the coming weeks', the decision to keep Auckland locked down for an additional week had no rationale whatsoever."
Ardern said the Cabinet would consider moving Auckland back to alert level 1 at the start of next weekend.
"But that doesn't explain why the hospitality industry for the entire rest of New Zealand will have to operate under alert level 2 restrictions that cripple profitability tomorrow [Saturday]," Seymour said.
"If they were confident in their contact tracing and self-isolation, Auckland would be able to operate with more freedom."
There have been no community cases reported for six days while businesses are still closed or restricted to non-contact methods.
But University of Auckland disease modeller Shaun Hendy says the shift up to alert level 3 was necessary.
"We went to alert level 3 when we didn't really understand the source of the new case that was discovered last weekend," Hendy told RNZ.
"Over the course of the week I think we've got a handle on that cluster, and especially with the very high testing rates that we've had this week, that will give them some confidence that the cluster is contained and that they do have the right people isolated."
