Prince William has appealed for an end to extremism in an address to survivors of a terrorist attack on Al Noor Mosque in Christchurch, New Zealand. 

The Duke of Cambridge also referenced the attacks on churches and hotels that killed over 200 people in Sri Lanka on Easter Sunday as he praised New Zealanders for standing together. 

"A terrorist attempted to sow division and hatred in a place that stands for togetherness and selflessness. He thought he could redefine what this space was," he said. 

"I am here to help you show the world that he failed." 

He said that a "warped ideology that knows no boundaries" was fuelling acts of violence around the world as he called on people to unite against extremism. 

He also said people of all faiths and backgrounds could "learn a great deal" from the compassion and forgiveness shown by Muslim families affected by the March 15 mosque attacks in which 50 people died.

"The example provided by New Zealand will prove to be of enduring value to all nations. What happened here was fuelled by a warped ideology that knows no boundaries," he said.

"The world has rightly united to fight the extremism that has made sorrowful brethren out of cities like New York, Paris, London, and Manchester and that has taken so many lives in Sri Lanka in recent days.

"And so too we must unite to fight the violent brand of extremism that has led to fatal shootings in a church in Charleston, South Carolina and a synagogue in Pittsburgh, Pennsylvania; a van attack on the streets of Finsbury Park in London; the murder of an MP in West Yorkshire; and now so many deaths in two mosques here in Christchurch."