The official death toll for the Christchurch earthquake has risen to 145 this evening, including victims of 20 different nationalities.

"We expect that number to rise," said Superintendent David Cliff.

The number of missing people for whom there are grave concerns remains at more than 200, he said.

"There remains a very real risk of masonry coming off buildings," Mr Cliff said, "as well as windows still smashing with those aftershocks."

A police officer has been assigned to each of the families of those still missing.

Fire Service spokesman Paul Baxter said the search and rescue effort was continuing, but there were no live rescues today and there have not been any since Wednesday afternoon.

But Mr Baxter said rescue teams were ready to be deployed to other areas at the first sign of life.

Superintendent Cliff understood families' frustrations who have not heard about their loved ones, but he said it had been a dramatic earthquake and the reality was that visual identification of the bodies was not easy.

"The biggest concern we have to returning the wrong loved one to the wrong family," Superintendent Cliff said.

Identification often relied on fingerprints or DNA, he said.

"Where we have specific information around the identity of a loved one, we will be doing everything humanly possible to get that person to their loved ones as soon as we can."

No new names of the deceased were released this evening.

The search and rescue teams have now gone through the whole area except for the blocks cordoned off around the Grand Chancellor Hotel. Teams were now going back more thoroughly through areas that have already been covered.

The Grand Chancellor Hotel has been assessed and a plan has been hatched to stabilise it as much as possible, though ongoing aftershocks make this a difficult task.

Power has been restored to just over 82 per cent of the city, including more than half of Sumner, which was particularly hard-hit.

Silence to remember victims

The Prime Minister has asked for a two-minute silence on March 1 "as a sign of unity for the people of Christchurch and out of respect for those that lost their lives".

"Canterbury will recover and we will do all we can to ensure it does.

"For now we must do all we can to show its people that all of New Zealand grieves with them."

John Key met with the families of those still missing earlier today, who have been waiting for days for news of their loved ones.

"They fear the worst but there is still a glimmer of hope," he said.

"The urban search and rescue crew made it clear that this was still very much a rescue effort, not a recovery.

"People can survive for considerable periods of time without water and food, and we're working as hard as we can to find those who might have survived this tragedy but might be trapped."

Mr Key thanked the family of Private Kirifi Mila - who was recently killed in Afghanistan - for cancelling the scheduled military funeral so that military resources could be redirected to Christchurch.

The Government will announce an economic package on Monday.

"It won't be the final solution. That's a very complex issue but it is an attempt for those who have lost their income and livelihood - and there is a substantial number of those - that they have some immediate help to get them through."

The packages are likely to last for a month, when further arrangements will be made.

"We are dealing with some very difficult circumstances here."

Mr Key said he had a spoken to a man this afternoon who had lost his home, his business and his wife.

"That is the magnitude of loss that some of them are facing. We have been inundated with support from around New Zealand and around the world, and it's important that those families know at this critical point in time that they are not alone, and they are not abandoned."

One woman he spoke to wanted to thank the Telecom workers who carried her through the CBD on a board to the hospital, despite her substantial injuries.

He said search and rescue teams had searched the entire central city except for the area around the Grand Chancellor Hotel, because of the danger the hotel posed if it collapsed.

He said a lot of buildings in the city would have to be rebuilt.

'This will not get easy in a hurry'

Christchurch Mayor Bob Parker has appealed for support and understanding for staff working to restore services in the city after Tuesday's devastating earthquake.

Mr Parker told a media conference this morning he knew residents were going through a difficult time.

"This will not get easy in a hurry," Mayor Parker said. "The next few days as we try to work as hard as possible on restoring services, we need to ask that you support us with your understanding of what we are doing.

"Nobody is sitting back watching this. Everybody is involved."

He said services would be restored as quickly as possible.

"Be patient - that's at this time part of your support for the overall Civil Defence operation."

Mayor Parker said workers were as focused as ever on their task.

"This might be a Saturday, and it might be that we haven't had good news stories we were hoping for in terms of finding people ... but for us this is just as important a day as the first day, the second day, the third day.

"Our approach will continue to be all of the people, all of the skills, to help us work through this tragedy. Our dedication has not moved one iota."

A number of eastern Christchurch residents were feeling more and more isolated, Mr Parker said, but he reassured all residents that - regardless of where they were - they were at the centre of workers' thoughts.

"Everybody is on deck. All hands are on the pump, but you do need to realise the scale of what is in front of us at the moment is utterly immense," he said.

He said the work that needed to be done dwarfed that following the September 4 earthquake and appealed for patience.

"The work we are doing right now is crucial to the restoration of services across the city."

Mayor Parker said that of the 1000 buildings that had been checked in the CBD, 60 per cent had been deemed to be safe, 17 per cent had been assessed as safe to access, but 20 to 25 per cent had been evacuated and deemed unsafe.

In the suburbs, 341 houses had also been red-stickered and evacuated. Another 500 had only limited access.

More investigation into the extent of damage to houses would be done today, he said.

"This is not a Saturday for us - it's another day of our immediate response."

Mayor Parker said conserving water would help the restoration of supply to the city.

Orion CEO Roger Sutton told the conference that power was now back on in more than 80 per cent of Christchurch.

Power equipment in some suburbs such as Sumner was not as badly damaged as previously thought, he said.

The numbers

145 confirmed dead
More than 200 missing
Nationals of more than 20 countries among the missing
329 people in welfare centres
About 120 patients moved to other NZ hospitals
About 180 aged-care residents moved out of Christchurch
About 1200 police in Christchurch, with 324 Australian officers sworn in yesterday
More than 600 search and rescue personnel including overseas teams
More than 1400 NZ Defence Force personnel working on the rescue effort

60 per cent of properties in CBD deemed safe, 17 per cent as safe to access and 20-25 per cent deemed unsafe
More than 4000 checks carried out on residential properties
341 suburban properties deemed unsafe and evacuated
Power restored to more than 80 per cent of Christchurch
70 per cent of general practices up and running
62,500 people remain without water and 100,000 have no sewerage service.