Emergency crews scoured the mangled wreckage of quake-hit Christchurch for a fourth day Friday but found only bodies and no signs of life as the death toll climbed to 113.
"These are very, very dark days for New Zealand," Prime Minister John Key said, adding that rescue crews refused to give up hope that people remained alive in the debris after Tuesday's 6.3 magnitude quake.
"We need a bit a bit of luck to try and find a few people that may still have survived this earthquake and are still trapped in those buildings," he told Radio New Zealand.
Police said 113 bodies had been retrieved from the rubble and were lying in a temporary morgue, without updating the figure of 228 listed as missing.
"There have been no rescues overnight, the body count continues to rise," superintendent Russell Gibson told TVNZ.
Rescuers have ruled out finding survivors at Christchurch's landmark cathedral, which lost its spire and where up to 22 people could be buried.
They also do not believe anyone remains alive under the collapsed CTV building, which housed a TV station and a busy language school for foreign students, and where as many as 120 people may have perished.
A pall of misery hung over Christchurch, but Gibson said international search and rescue specialists who had flown in to help the rescue effort had told him to remain optimistic.
"The (rescuers) -- from Australia, from Japan -- all tell me that they have worked on buildings which look just like the CTV building and many days after the collapse they continue to pull people out," he said.
But civil defence minister John Carter warned the toll would rise, possibly sharply, as emergency crews who had been concentrating on the worst-hit buildings in the city centre fanned out into other areas.
"They are now going into places such as alleyways where people would have been coming back and forward from work to go to lunch, where they suspect that there are people under the rubble of the facades... that may be dead," he told reporters.
Police have cordoned off the city centre as they use sniffer dogs, purpose-built cameras and listening devices in the hunt for survivors. The last survivor was pulled out of the rubble on Wednesday.
They have also vowed to crack down on criminals after about a dozen cases of post-quake looting in Christchurch, with Gibson saying he was "sickened" by thieves who had tried to gain access to properties by impersonating rescuers.
On Thursday authorities released the first names of quake victims, listing four people including two babies aged five months and nine months.
Japan said that at least 26 of its citizens who had attended the foreign language school in the CTV building school were missing. Twenty Chinese students were unaccounted for, state television in China reported.
Twelve Filipinos were believed to have been inside the CTV building, along with a South Korean brother and sister who were also listed as missing. Their father arrived in Christchurch Thursday to search for the pair.
"My son and daughter must be alive," said 57-year-old Yoo Sang-cheol, according to South Korean news agency Yonhap.
"I hear that some of the injured people have not yet been identified, so I'm going to go to the hospitals immediately," he said. "I'm certain that my son and daughter will be among them," he said as he burst into tears.
Two British nationals are also known to be among the dead.
Japanese search-and-rescue experts were on the scene and combing the CTV site in the shadow of the listing, 26-storey Grand Chancellor Hotel, Christchurch's tallest building, which was at risk of collapse.
Power has been restored to much of the city, but many people remain without water. Thousands of residents, rattled by numerous tremors in recent months, have been staying with friends and relatives elsewhere.
Christchurch was hit by a 7.0-magnitude earthquake in September, which damaged 100,000 buildings but miraculously caused no deaths. New Zealand has not suffered such a disaster since 256 people died in a 1931 quake.