Officials in Christchurch have raised the death toll from Tuesday's earthquake to 147 - more than 200 others are still missing.
Engineers and planners say the city's central area may be completely unusable for months to come and that at least a third of the buildings must be razed and rebuilt after the 6.3-magnitude quake.
Police Superintendent David Cliff said that 'certainly we expect that number to continue to rise'.
'There are more than 200 people missing in the worst-damaged parts of the city,' he told reporters.
His comments suggest the eventual death toll could make this New Zealand's deadliest disaster ever.
The country's worst disaster was the 1931 Napier earthquake on North Island in which at least 256 people died.
Earlier, Police Inspector Russell Gibson said rescuers had spotted more bodies in the wreckage, which likely would be retrieved Sunday.
The multinational team of more than 600 rescuers scrabbling through wrecked buildings in the central city last pulled a survivor from the ruins at mid-afternoon Wednesday, making it nearly four days without finding anyone alive.
Rescue coordinator Jim Stuart-Black said Sunday that rescuers continued 'to look in every possible place for survivors'.
'We are still in active rescue mode ... but we are also realistic that we are starting to move into the miracle stage of the operation,' he said, with survival becoming less likely six days after the quake.
Rescue and recovery efforts were hampered by continuing aftershocks, which sent masonry tumbling down, and a cat sparked a false alarm over a possible survivor on Saturday.
Prime Minister John Key said the government would announce an aid package Monday for an estimated 50,000 people who will be out of work for months due to the closure of downtown.
Mr Key, who spent some of the afternoon talking to families who lost loved ones in the disaster, called for two minutes of silence on Tuesday to remember both the victims and the ordeal of the survivors.
'This may be New Zealand's single-most tragic event,' Mr Key said yesterday.
Prayers were said for the dead and missing at church services Sunday in Christchurch and across New Zealand, but church leaders cancelled a planned multi-denominational service in a Christchurch park because of concerns it could block access roads for essential emergency services.
'As our citizens make their way to church this Sunday they will be joined in prayer by millions around the world,' Christchurch Mayor Bob Parker said.
'For now we are truly comforted by the thoughts and prayers of so many.'
