GRAPHIC CONTENT WARNING: THIS STORY CONTAINS DETAILS AND LANGUAGE WHICH READERS MIGHT FIND UPSETTING

"Your father was a garbage man and you became the trash of society… you deserve to be buried in a landfill."

There were strong words for mass killer Brenton Tarrant in court this morning as the son of a slain mosque elder called him a "peasant" who could never change the world.

Haji Mohemmed Daoud Nabi, 71, was shot dead at Al Noor Mosque on March 15 last year.

The retired engineer and father-of-five fled his homeland Afghanistan during its war with Russia and brought his young family to New Zealand in 1979.

Today, his son Ahad Nabi, wearing an NZ Warriors rugby league jersey, stood in the High Court at Christchurch during the third day of sentencing and stared down the gunman before reading his victim impact statement.

The hand holding his statement shook as he read, his other fist clenched.

"You hurt my father, but you never took him away from me – what I mean by this is that you physically hurt but you gifted my father with becoming a martyr," Ahad said.

"Your actions on that day displayed what a coward you are… you shot at defenceless people… your actions were of gutless character.

"There's nothing heroic about shooting people from behind and people not having a chance of defending themselves.

"I do not forgive you for what you have done. While you are in prison you will come to reality that you are now in hell – and only the fire awaits you."

Ahad didn't mince his words when he directed his words at Tarrant in the dock.

"A peasant like you will never change the human race. Your wish is to make this world a racist cult of one colour but you'll never succeed."

He said Tarrant was "scum of the world" and should never be freed.

"I ask that he be put in mainstream prison and stop wasting taxpayer money by giving him special protection.

"Coming back to this maggot, my 71-year-old dad would have broke you in half if you challenged him to a fight.

"But you are weak – a sheep with a wolf's jacket on for only ten minutes of your whole life."

Haji-Daoud Nabi Haji Nabi was shot and killed during the Christchurch mosque shootings March 2019. Photo / Supplied

As he walked out of the courtroom he called Tarrant a "piece of s***".

The 29-year-old Australian national initially pleaded not guilty to his offending but later admitted 51 charges of murder, 40 counts of attempted murder and one of engaging in a terrorist act laid under the Terrorism Suppression Act 2002.

He is being sentenced this week before Justice Cameron Mander.

Ahad is one of 22 people reading victim impact statements today. The sentencing hearing continues this afternoon.