What started out as a sombre occasion in the memory of those who died in last month's Christchurch earthquake finished as a rallying call for the city to get back on its feet.

Tens of thousands of people turned out for a memorial service at Christchurch's Hagley Park today, where Prince William linked Christchurch with New York in the wake of 9/11 as he paid tribute to the courage of New Zealanders and of Cantabrians, telling them Kia Kaha, be strong.

Speaking on behalf of his grandmother the Queen, Prince William used the words she used when expressing her feelings for New Yorkers in the wake of the 2001 terror attacks on the twin towers of the World Trade Centre.

"My grandmother once said that grief is the price we pay for love. Here, today, we love and we grieve."

He told the thousands of Cantabrians at North Hagley Park they were an inspiration for the way they had coped after February 22's devastating earthquake.

While New Zealanders were noted for courage and determination, "to see them so starkly demonstrated over these terrible, painful months has been humbling. Put simply, you are an inspiration to all people.

"I count myself enormously privileged to be here to tell you that.

"We honour the lives and memories of all those who did not survive the earthquake - New Zealanders and those from many countries around the world, who came to this city as visitors or to make it their home. Our thoughts and our prayers are with their families wherever they may be."

He ended with the simple message Kia Kaha, Maori for be strong. It was a message that brought tears to the eyes of mourners.

After the service, the Prince spoke to people from the bereaved families, who were in 400 seats specially laid out in front of the main stage. A pile of broken bricks and rubble sat in front of the stage, lined on each side by New Zealand flags.

He patted one young girl on the shoulder and then her head, before mingling with members of the search and rescue teams and shaking the hands of hundreds of people as he walked towards a roped area where a commemorative young oak tree was freshly planted. He shovelled in dirt around its base.

His address to the mourners was after two minutes' silence at 12.51pm, exactly 24 days after the magnitude 6.3 earthquake smashed Christchurch, killing an estimated 182 people.

As the mourners stood for the silence, balloons in Canterbury's famous sporting colours - one red, one black - floated up.

As musical tributes were performed by singers including Dave Dobbyn, Hayley Westenra and Dame Malvina Major, people wiped away tears.

However, the mood lifted when a kite flying the sign "Rise up Chch" rose above the mourners while Prime Minister John Key spoke.

Mr Key spoke about the loss of lives, but also about the city's resilience.

"Here in the beautiful Hagley Park today we see the face of a city that is broken but not beaten," he said.

Mr Key said the quake had "left scars that will never be erased from our land or from our hearts".

He told the crowd they were gathered to remember those who had been lost, and to express their grief and sorrow.

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

Christchurch Mayor Bob Parker spoke of a city struggling to understand the tragedy, suffering such losses, and battling to see a future.

Christchurch owed it to those who died to rebuild; a safe city where such devastation could never be repeated, a city where businesses had a future, and where the names of those who died were commemorated, he said.

"To give meaning to this terrible event we have to have faith in ourselves."

The park was teeming with people, many of them wearing the Canterbury red and black.

Musician Dave Dobbyn sang his anthem Loyal - his catch cry hit adopted by New Zealanders as an expression of patriotic pride for the past two decades. He finished with "God bless you, and keep you in peace".

Before the service, people stood and applauded as teams of emergency workers, including Urban Search and Rescue (USAR) members, arrived.

Family members, each carrying a yellow rose, began to take their seats from 10am.

God Save the Queen was sung, before silence enveloped the ceremony.

After a conch shell was sounded to begin the service Henare Rahiihia Tua from Ngai Tahu's main sub-tribe, Ngai Tuahuriri, opened the service with prayers of thanksgiving and a welcome.

Among those with Prince William in the official party were Mr Key and his wife Bronagh, Governor-General Sir Anand Satyanand and his wife Susan, Lady Satyanand, Mr Parker and his wife Jo Nicholls-Parker, Australian Prime Minister Julia Gillard and her partner Tim Mathieson, Australian Governor-General Quentin Bryce and her husband Michael Bryce and Australian Opposition leader Tony Abbott and his wife Margaret.

Singers Hayley Westenra sang Amazing Grace, and Dame Malvina Major You'll Never Walk Alone, a song linked with resilience in the face of tragedy.

Religious tributes dominated the latter stages of the service, with the Lord's Prayer, bible readings, and prayers offered by the Buddhist, Muslim, Jewish, Christian, Hindu and Baha'i faiths, followed by a blessing.

Salvation Army volunteers worked their way through the crowd handing out sunscreen, and a "Rise up Chch" sign hanging from a kite floated over the crowd throughout the service.

Groups of people seated on cushions, blankets and fold-out chairs around the park listened quietly to speeches, prayers and musical tributes.

When Westenra sang Amazing Grace, many wiped away tears, and a video showing the relief effort drew applause and whistles from the crowd. Many children sat on their parents shoulders to get a better view, as everyone stood to sing the national anthem.

Images of urban search and rescue workers and volunteers were greeted with a spontaneous standing ovation, applause and whistles.

Two cornerstones of Canterbury life knocked askew by the quake were aired in musical form - Conquest of Paradise, the theme song for rugby's now homeless Crusaders, and a performance of the choir of Christchurch Cathedral, whose place of worship was shattered by the quake.

One Christchurch resident, Lisa McNire, said the service was touching and brought people together.

"It's a new beginning for the city," she said.

Following the service, the Prince spoke individually with the families of the quake's victims, then worked his way along fencing, greeting other Cantabrians who had turned out for the event.

Katelyn Kindelan, 10, was among those to get a one-on-one chat with the royal visitor.

"I asked him to sign my book but he said he couldn't,'' she told NZPA.

"But he shook my hand and was really nice."

Catherine Bachop, 25, and her son Lexis, 8, also had a chance to speak to the prince.

"I told him to say hi to Kate for me and he said he would," Ms Bachop said.

Ms Bachop, who lives in the suburb of Shirley, said she was really pleased with how many people had come to the service.

"It turned out really well and the weather was great," she said.

Maureen Dixon, 64, from Christchurch, said the service was "wonderfully inspiring".

"It gave us all the hope and inspiration that we needed to get going again.

"I was very, very touched by a lot of what was said and particularly the care that people have shown."

Aleysha Knowles, of Perth, Australia, used to work for Canterbury TV and has been back in Christchurch for funerals of friends and former colleagues.

She said the service was "very, very beautiful".

"It was really moving, but it was also giving a lot of people hope," she said.

"It spoke about the future and rebuilding in Christchurch, which I think is important to the people that are here and will obviously stay here, because they need to now look forward."

Peter Haggett, 49, of Christchurch, said he doubted anyone would leave the service without a tear in their eye.

He said he and others would be leaving with mixed emotions.

"I think it's a tribute to those who have lost their lives and a way to thank the search and rescue guys, defence, police... everybody."

"It's been a very emotional day for everyone."