Authorities say they may now have been mistaken over reports of a woman's voice from the rubble of a Christchurch chapel this morning.

Hours after Prime Minister John Key warned the hopes of finding survivors were fading, search teams swung into action after it was claimed one worker had heard a "faint" female voice about 9am, local time. But those hopes were dashed when a Sky News reporter at the site said emergency workers had revealed they may have been mistaken about the voice.

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Search teams are looking for at least one person who has made contact with police from under the rubble in central Christchurch this morning despite warnings from New Zealand's Prime Minister that hopes of finding more survivors were fading.

Rescuers will mount an operation that could take up to five hours after hearing a "faint" female voice from the rubble.

"We got reports of a female voice ... from a void in the structure," an Australian involved in the rescue operation, Fire and Rescue NSW Superintendent Gary Picken, said this morning.

"It's [in] the old Holy Cross Chapel."

The news came soon after Civil Defence Minister John Carter said rescue teams were heading into the city's suburbs for the first time since Tuesday's devastating 6.3 magnitude earthquake.

Prime Minister John Key said earlier this morning that search and rescue workers are now focusing on the recovery of bodies rather than the rescue of survivors, two days after a devastating earthquake.

Mr Key said emergency workers were "not getting positive signs" as they looked for sounds or signs of life under the rubble, as he warned New Zealanders to brace themselves for a rising death toll.

The confirmed death toll is 71 and 300 people are believed to be missing, but authorities have said the number of people unaccounted for may include many who fled the city centre after the quake and have not contacted officials since.

"We have currently in morgues across the city 71 people confirmed dead. We are aware there are other bodies but we haven't got a number on that," Civil Defence Minister John Carter told reporters.

Fears for one Australian

A Department of Foreign Affairs and Trade (DFAT) spokeswoman said "we now have concerns for one Australian in Christchurch who has not yet been located".

"It is a fluid situation and we are continuing to receive information about Australians in Christchurch. Sadly, we need to prepare for the possibility of more Australian fatalities."

The spokeswoman said 1581 Australians were confirmed safe by DFAT staff, while 96 Australians returned home to Sydney and Brisbane on board C130 and C17 air force planes last night.

Mr Carter said about 2500 people have been injured, 164 seriously.

Police said no survivors had been pulled from the rubble since yesterday afternoon and it had been more than 24 hours since any text messages had been received from anyone trapped under the debris.

"We are hopeful that we might find survivors but as time passes hopes fade," Superintendent Russell Gibson told TV3.

But police said they were still holding out hope that people were still alive in wrecked buildings.

"Experts tell me that there are pockets within a number of these buildings, and providing people haven't been crushed there's no reason that we will not get people out of there," Superintendent Gibson said.

Superintendent Gibson said 50 to 100 people were believed to be missing in one of the worst-hit buildings, the CTV site, following the 6.3-magnitude aftershock, but stressed the numbers were speculative.

Victim's home burgled

The home of TV producer Donna Manning, believed dead in the Canterbury TV building, has been robbed overnight.

Ms Manning's children had been keeping a vigil outside the building when the house was robbed, her brother Maurice Gardiner told TV1.

Mr Gardiner said the actions of "some uncouths" had increased the suffering of Manning's family.

"Bad things happen. We are all suffering bad things as a result of this earthquake that we can't help."

While people across the city were suffering, he said many were in the position that their valuables had been left in the open.

Authorities ordered a 6pm curfew last night, arresting six people for looting.

Tallest hotel remains standing

Fears for the collapse of Christchurch's Hotel Grand Chancellor were not realised overnight.

The city's tallest hotel was expected to topple after suffering extensive damage in the quake and showing signs of buckling yesterday.

Witnesses said the tower had subsided three metres in a matter of minutes.

Hundreds of rescuers swarmed over twisted and smoking buildings yesterday in a frantic search for survivors.

Emergency services cordoned off central Christchurch. Rescuers from the United States, Britain, Taiwan and Japan are expected to join the operation today. More than 1000 workers were expected to comb though shattered Christchurch buildings.

The new rescue teams would allow the search of wrecked buildings to be widened.

A national state of emergency has been declared and the central city has been under curfew with soldiers patrolling in armoured personnel carriers.

Thousands of people spent a second night in emergency shelters set up in local schools, sports grounds, and at a race course. Fresh water supplies were being distributed from schools and portable toilets set up around the city as services were disrupted.

stuff.co.nz, smh.com.au, theage.com.au, AFP, Reuters and Glenda Kwek