Kia kaha.

With the simple Maori phrase for "be strong", Prince William drew applause and tears from tens of thousands of mourners at today's service to honour victims of the Christchurch earthquake.

His address in North Hagley Park was brief but notable for its poignancy, striking the right note for mourners as they remembered the estimated 182 people killed in the February 22 earthquake.

He conveyed the deep sympathy of his grandmother, the Queen.

"My grandmother once said that grief is a price we pay for love.

"Here today we love and we grieve.

"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."

Prince William said he also brought a personal message.

"It arises from seeing this tragedy unfold from afar.

"It is a message about strength through kindness, about fortitude.

"For you who are so close to these events and to have lost so much, it must be hard to grasp the degree of admiration, indeed awe, with which you are regarded by the rest of the world.

"Courage and unabated determination have always been the hallmark of New Zealanders, of Cantabrians. These things the world has long known. But 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."

The Christchurch community more than any other in the world could appreciate the full horror of what was unfolding in Japan, Prince William said.

"In the last two days, I have heard tales of great tragedy but also of extraordinary bravery and selfless courage," he said.

"Throughout, one phrase unites them all. With the heartfelt good wishes and those of the Prince of Wales and other members of my family, I say it to you now.

"Kia kaha, be strong."