Rescuers were on the verge of recovering bodies from the Christchurch Cathedral's collapsed spire last night, after 10 painstaking days spent securing the fragile structure.

New Zealand and American search and rescue teams were working around the clock, forensically picking apart the rubble where 22 bodies are believed to be buried.

The cathedral's dean, Peter Beck, said Urban Search and Rescue (Usar) workers had made their way into the second storey of the structure and had retrieved three of the spire's bells. Most of the people trapped inside were thought to be in the stairwell near the base of the tower when its roof fell.

Usar workers are working slowly and meticulously so as not to further degrade the historic structures, or damage the hidden bodies.

Mr Beck said: "They are very sensitive to the fact that this is the cathedral but at the end of the day I have said to them we can rebuild, we cannot rebuild these lives and we need to be as careful as we can with them."

He said a duty priest was on standby - the moment a body was found, work would temporarily cease for a prayer at the site. This would occur each time a body was found.

An entire wall of the cathedral's stone tower has been torn away by diggers, revealing the huge and complex task ahead. Broken masonry is stacked 10 metres high within the old spire, much of it precariously placed.

The recovery process is difficult. A specially constructed steel capsule must be lowered by crane into the tower so the workers can enter the building safely.

The workers place a series of cameras in the rubble to search for bodies, centimetres at a time. If nothing is found, a digger carefully begins picking away at the rubble again. Fire Service search co-ordinator Paul Baxter said Usar workers were preserving as much of the building as they could.

Dame Malvina Major lent her support to the cathedral recovery yesterday, singing Pokarekare Ana in the empty streets nearby. She told the Weekend Herald everyone she knew had helped out in some way - with shelter, or baking - and she wanted to play her part. "I keep thinking, what can I do, what can I do. This is just a small thing ... I hope I can contribute more soon."

Dame Malvina, whose home is near the epicentre of the September quake, said she had fond memories of singing in the Anglican building.

"I've sung there many times. It's quite surreal to see it fall apart like this. The city has lost its heart."

She was teaching at the University of Canterbury's Ilam campus when the quake hit, and was nearly knocked off her feet.

Mr Beck said there was a strong desire to rebuild the cathedral, which also has significant damage to its south porch.