Auckland's mayor Phil Goff says the lockdown remains the best way for the city to eventually get back to level 1.
Cabinet has decided to keep Auckland in alert level 4 until at least 11.59pm on Tuesday 31 August. The rest of the country will remain at alert level 4 for another four days, until 11:59pm on Friday.
So far 99 of the 107 cases of this Delta cluster are in Auckland, with the remaining eight in Wellington.
The Crowne Plaza in the Auckland's CBD is at the centre of an investigation into how Delta got into the community after genome sequencing linked the outbreak to a Sydney returnee who was isolating there.
Six members of the public were using a thoroughfare through the hotel, which is only separated from isolating guests by a perspex divider, at the time the positive case was in lobby.
Goff said Auckland could not have come out of lockdown at the moment, given there are some 13,000 contacts in the cluster so far.
He said the prime minister said that the current level of transmission is about six, meaning that for every person in the community with Covid-19 they will pass it on to about six people.
"And that needs to come down to less than one to know that you are on top of the spread of the virus."
Goff said to beat the virus it is important to act promptly and decisively and he has not spoken to anyone who believes that the level 4 status could have been lifted in Auckland at this time.
He said level 4 makes life difficult for everyone but he is particularly worried about those who have no income because they are not able to work at the present time and those who are living alone or who are separated from their families.
"All of that's tough, but equally, all of us know that if we want to get back to level 1 the best way, the quickest way of doing that is all of us following the rules, acting collectively, making sure that what we do keeps ourselves, our family and our community safe."
Goff said the council's losses will not be quite as dramatic as during the last lockdown because the money coming from the airport and port has already been lost.
He said Auckland Council will lose about $5 million a week through lack of public transport fares and parking fees, as well as all the facilities that the council usually has out for hire being closed down.
But Goff said when the council put together its emergency and recovery budgets it did so conservatively on the basis that another lockdown was a possibility.
"So we're confident provided this lockdown can be handled within the space of approximately a month, that we'll get through this because we've planned for it."
He said the longer the lockdown drags on the harder it is for everybody.
Goff said those council staff who can are working from home, while others are being mobilised to help with Covid-19 and doing roles such as preparing meals for the homeless and they may help with Covid tracing if needed.
He said the council has had discussions with the police about where the regional borders are in case Auckland ends up in a different alert level from the rest of the country.
"The south will be on the border which is just south of the Bombay Hills, in the north it will be just north of Wellsford."
Goff warned Aucklanders that hopping in the car and driving to the holiday bach is putting everybody at risk.
He said ideally the Covid-19 facilities would be outside of Auckland but that is not realistic in a short timeframe.
But he said despite the difficulties of shifting the facilities outside the city boundaries, it is something he would like the government to continue to consider.
Goff said he is still pushing for people in Auckland, especially more vulnerable populations, to be given vaccination priority, as he did last year.
He said as the gateway city, Auckland is the city that's most likely to go into lockdown and the latest Covid-19 outbreak just proves that point.