Rescue operations have focused on the city's central business district, which bore the brunt of the quake [Reuters]
New Zealand must expect the death toll from Tuesday's quake that has devastated the country's second biggest city Christchurch to rise, the prime minister has said.
"We do have to brace ourselves that while the official toll is 71 that number will rise today and tomorrow," John Key told Television 3 on Thursday.
He said there there were no positive signs coming from major buildings where people were believed to be trapped.
Police, however, said they were still holding out hope that people were still alive in buildings damaged by the 6.3-magnitude earthquake.
"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," shift commander Russell Gibson said.
However, he added that signs were not good for finding anyone alive in a flattened building that housed a local television channel and an English language school, which had many Japanese students, with as many as 100 people still in the building.
The death toll was previously put at 75 but officials revised that. "We have currently in morgues across the city 71
people confirmed dead. We're aware there are other bodies but we haven't got a number on that," said John Carter, the civil defence minister.
He said early reports of up to 300 other people missing was speculation and it was not known how many were unaccounted for.
Carter said around 2,500 people have been injured, 164 seriously.
Rescue efforts hampered
Rescue teams combed through rubble for a second night under searchlights but searchers found no more survivors from the earthquake.
Rescue operations have focused on the city's central business district, which bore the brunt of the quake.
Fears that the 26-story Grand Chancellor Hotel, one of the city's tallest buildings, might collapse at any moment
triggering a domino-effect with other unstable buildings have hampered rescue efforts.
"It's incredibly dangerous ... if it hits the ground it will create a significant shock wave," local mayor Bob Parker said.
The city has been shaken by more than 100 aftershocks since the initial shake, bringing down more debris.
Rescuers from the United States, Britain, Taiwan and Japan are expected to join the operation on Thursday. More than 1,000 workers were expected to join the operation.
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.