Police Superintendent Dave Cliff said four more bodies had been pulled from rubble by recovery teams in the shattered city of Christchurch overnight Tuesday, taking the total death toll to 159.
Many more people remain missing, and Cliff has said the final tally is likely to be around 240.
More than 900 urban disaster specialists are working at sites across the southern city picking through the remains of wrecked buildings and clearing away debris, as the massive operation moved into its second week.
No one has been pulled alive from the rubble since 26 hours after the Feb. 22 quake, and officials are pessimistic about finding any other survivors.
The operation to recover bodies has been slowed by near constant aftershocks that have rumbled through the city, threatening to bring further debris raining down from damaged buildings.
Authorities have appealed for patience from families waiting for news of missing relatives, saying that the remains of some people who were caught in falling buildings can be identified only through DNA testing or dental records.
"There may be some cases where, because of the enormous forces involved in this, that it may not be possible to retrieve bodies in all cases," Cliff told reporters Wednesday. "We need to alert people to that possibility."
Among those listed as missing are an unknown number of students and staff from Japan, China and other countries who were at an English language school that was housed in one of two office buildings that completely collapsed in the quake. Police said last week that up to 120 bodies were inside the Canterbury Television, or CTV, building, where the language school was located.
Strong winds were hampering rescue and recovery operations Wednesday, threatening to bring down bricks and masonry from already-damaged buildings and spreading clouds of dust around the city.
Some of the city's 350,000 residents donned face masks when they went outside to protect themselves from the dust.
The magnitude 6.3 quake struck within a few miles (kilometers) of downtown Christchurch, when the city was bustling with workers, shoppers and tourists going about their weekday afternoon activities. It brought down or badly damaged office towers, churches and thousands of homes across the city.
Prime Minister John Key said Tuesday that a commission of inquiry would investigate the circumstances of the quake, including a detailed look at why the CTV building and the other hardest-hit, the Pyne Gould Guinness building, collapsed.
The owners of the CTV building said in a statement issued by their lawyers they would cooperate fully with the inquiry.
Lawyer Ken Jones said the owners had commissioned a detailed structural engineers report after an earlier quake on Sept. 4, and that the report found superficial damage to the building from that temblor but raised no structural issues.
Also Tuesday, towns and cities across New Zealand fell silent for two minutes exactly one week after the quake struck, in a national commemoration.