The status has to be reaffirmed every seven days, and Key said on Monday that given the extent of the devastation it's still needed.
"I think they will be there for quite some time actually," he told TV1's Breakfast Show.
His comments came after people returned on Sunday to the stricken central business district for the first time, nearly two weeks after the deadly magnitude 6.3 quake.
But their return was not without difficulty and anger, leading civil defence director of planning Baden Ewart to say things would improve.
Police lifted the cordon in areas of the CBD at 8am on Sunday, allowing residents and business owners to retrieve cars and valuables left behind before the quake. The public was allowed access from 2pm.
The empty streets were suddenly clogged with traffic as residents rushed to check the damage to their buildings during the 6.3 magnitude quake that struck on February 22.
Ewart acknowledged that some residents and business owners were frustrated at delays in getting into the areas, and asked people to be patient.
"We are looking at improving our game. There is a balance between safety and security on the one hand and enabling access on the other, and I think today it's fair to say we didn't get that balance right, but we have learnt from that.
"We'll do a better job next time."
He said people who did not have the proper credentials were turned away, and others were also trying to get into the restricted areas in the CBD.
The death toll officially rose to 166 on Sunday, with an expected final toll of more than 200, and police named 15 more of the dead, to bring the number of those named to 41.
Search teams have completed their work at the Canterbury TV building in the CBD, where more than 100 people are believed to have died.
Urban Search and Rescue (USAR) spokesman Paul Baxter told a media briefing crews are now focused on the Forsyth Barr building.
Education Minister Anne Tolley was able to provide good news to the region's teachers and students.
She said 31 schools indicated they would be open for students from today or over the next few days.
A further 55 schools were structurally sound and could open for staff immediately, with opening dates for students expected soon.
Treasury announced on Sunday that the cost of the quake to the country will reach up to $NZ15 billion ($A10.99 billion) and will knock gross domestic product growth back by 1.5 percentage points.
However, there was a silver lining to the dire financial news, with the prediction of good news to the region when rebuilding is underway.
"From 2012, the recovery will bring a sizeable boost to residential, commercial and infrastructure investment, placing upward pressure on prices depending on the rate of rebuilding," Treasury said.
Offficials have estimated one-sixth of Christchurch's 390,000 population -- some 65,000 people -- have fled, terrified by incessant aftershocks or because their workplace has been damaged or destroyed.
Mayor Bob Parker has warned it could be months before parts of the city reopen, and though the government has underwritten all employees' wages for six weeks in a bid to protect jobs, prospects for the CBD's 52,000 workers are uncertain.
"I know already that populations in other towns in the South Island have risen exponentially as people from here who have the ability to or have a holiday home or have a contact relocate," Parker said.
The aftershocks continued overnight, with several quakes measuring more than 3 rattling the area.
Cabinet will on Monday discuss the quake, with an inquiry into building collapses and a memorial day on the agenda.
