Photo taken on March 16, 2019 shows cards and flowers people placed to mourn the victims of the attacks on two mosques in Christchurch, New Zealand. (Photo:Xinhua)

A year after New Zealand's deadliest mass shooting, a survivor who became a worldwide symbol of forgiveness says he still feels no anger about the attack, but misses his wife so much he forgets she is gone.

Farid Ahmed, whose wife Husna was one of 51 people killed by a gunman at the Al Noor mosque in Christchurch, reached out within days of the attack to express his forgiveness to the family of the man responsible for the massacre.

He has since been a public face of the survivors, and has met Australian Prime Minister Scott Morrison and US President Donald Trump.

"I have taken the tragedy as an opportunity to spread a message of peace and love," Ahmed told Reuters through tears in an interview ahead of the anniversary of the deadliest attack in the country's history. 

"I never felt angry but I ask what was her crime? She didn't hate anyone."

Ahmed has written a book, named Husna's Story, about his wife, the massacre and what he describes as his "journey to forgiveness." 

All proceeds are to be donated to an ambulance charity.

Husna was shot dead by the gunman while running from the building to look for Ahmed, who is confined to a wheelchair from an earlier accident. 

Sometimes he still imagines her sitting beside him in his car, he said.

"I'm driving [and] I look at my side and I feel she is there and suddenly not there," he said.

The alleged mosque attacker Brenton Tarrant, an Australian national, is due to go on trial on June 2 facing terrorism charges plus 51 counts of murder and 40 of attempted murder over the killings.

Reuters / AFP