All of New Zealand south of the Auckland boundary will move to Alert Level 3 on Tuesday at 11.59pm, while Auckland and Northland will remain in full lockdown.
During today's Covid-19 briefing, Prime Minister Jacinda Ardern warned that it was likely that Auckland would remain in lockdown for a further two weeks.
"This is so we can get Delta under control."
She later clarified Northland may not be facing the same length of time in Alert Level 4 as Auckland, with the length of time for the two regions to be considered at the next Cabinet meeting on Monday.
Ardern said they needed to be confident Delta was under control and stamped out.
She said Northland was included in the full lockdown extension due to the recent case in Warkworth.
"We are concerned of the potential movement of people in northbound journeys."
She said it was unlikely Auckland and Northland would be treated the same "in the long term".
"When we confirm Auckland's settings in a few days' time, this coming Monday, we will update you on our thinking on the region."
The Alert Level 3 settings for the rest of New Zealand would next be reviewed on September 6.
"We may be seeing the beginning of a plateau in cases," Ardern said today, after 70 new cases were reported.
"We have evidence of what we are doing is working, but caution is required.
"By far the most effective tool we have right now is Level 4."
Ardern announced earlier this week the rest of the country would remain in Level 4 until at least 11.59pm on Friday.
She said at the time Cabinet decided to keep the rest of New Zealand in lockdown until that time to compile "additional data and assurances to whether the virus has spread from the existing".
On Friday, there was 70 new community cases, all in Auckland. It brings the total number of community cases in Auckland to 333, and the number of cases in Wellington stands at 14.
The total number of cases in the Delta outbreak is now 347.
Earlier this week, Covid-19 Response Minister Chris Hipkins said Government planners had created a variety of scenarios "for different challenges up and down the country".
"That includes a variety of different regional boundaries that could be applied - whether it's a regional boundary for Auckland, a regional boundary for Auckland and the Coromandel and the Bay of Plenty and Waikato, a regional boundary for Wellington - these are all possibilities that are on the table."
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