PM says scars of Christchurch quake will never be erased

Prime Minister John Key says last month's devastating Christchurch earthquake has left the scars that will never be erased.

But he also had a message of hope for the crowd of thousands gathered at this afternoon's memorial service at Hagley Park in Christchurch -- the city will be rebuilt.

Mr Key told mourners the quake had "left scars that will never be erased from our land" and it was time to remember those who had been lost, and to express grief and sorrow.

He paid tribute families who had lost loved ones, many of whom were among those gathered.

"Let us remember them -- they are the faces of a Christchurch that will never be as it was again," Mr Key said.

"We do not know your pain as you do, but your experience haunts us.

"I can only say to you that New Zealand is here for you, and we hold you in our hearts."

The quake had altered the lives of everyone in Christchurch and no words or deeds could change that, Mr Key said.

"So today we remember Christchurch as it was, and we treasure that memory."

It was a time of great uncertainty and the recovery would be slow, painful and difficult, but it was also a time to celebrate the power of community.

"We have witnessed in these past three weeks the very best of the human spirit. We have seen the coming together of a city, and of a nation," Mr Key said.

"I have seen people who are resilient, capable, practical and compassionate.

"New Zealanders have been generous and brave, and we are resolute -- this city will be rebuilt."

Mr Key thanked the thousands of people who had helped out since the February 22 quake.

"On behalf of all New Zealanders, I say thank you. I also pay tribute to the resilience of every Christchurch citizen who has done what must be done, who has resisted despair and had the bravery to go on.

"These have been such difficult days."

Labour leader Phil Goff told the crowd it was a time to grieve, a time to be grateful and a time for hope -- "hope borne from the resilience and determination of Cantabrians to come through this".

He also paid tribute to the renaissance of "a strong Kiwi community spirit" and thanked the rescue workers, volunteers and community groups who worked tirelessly to help others after the quake.