New Zealand's Ardern vows never to speak killer's name

New Zealand Prime Minister Jacinda Ardern vowed on Tuesday never to utter the name of the twin-mosque gunman as she opened a sombre session of parliament with an evocative "as salaam alaikum" message of peace to Muslims.

"He will face the full force of the law in New Zealand," Ardern promised grieving Kiwis, while promising that she would deprive the man who slaughtered 50 people in Christchurch of the publicity he craved.

"He sought many things from his act of terror, but one was notoriety," she told assembled lawmakers of the 28-year-old Australian accused of the slaughter.

"That is why you will never hear me mention his name. He is a terrorist. He is a criminal. He is an extremist. But he will, when I speak, be nameless."

"I implore you: Speak the names of those who were lost rather than the name of the man who took them."

Dressed in black, the 38-year-old leader opened her remarks in parliament with the symbolism of the greeting uttered across the Islamic world.

"Wa alaikum salaam wa rahmatullahi wa barakatuh" she said. 'May the peace, mercy, and blessings of Allah be with you too.'

She closed her address by noting that "on Friday, it will be a week since the attack, members of the Muslim community will gather for worship on that day. Let us acknowledge their grief as they do."

Her comments came as dozens of relatives of the deceased began arriving from around the world ahead of expected funerals which have already been delayed far beyond the 24 hours after death usually observed under Islamic custom.

The slow process of identification and forensic documentation has so far made burials impossible, augmenting families' grief.

Javed Dadabhai, who travelled from Auckland to help bury his cousin, said families and volunteers were told: "it is going to be a very slow process, a very thorough process".

"Some families have been invited to have a look at their family members... the ones that are easiest to recognise, but we are talking about three or four." "The majority of people still have not had the opportunity to see their family members," he told AFP.

In the wake of the mass shooting, Ardern has promised to reform New Zealand gun laws that allowed the gunman to legally purchase the weapons he used in the attack on two Christchurch mosques, including semi-automatic rifles.

New Zealanders have already begun answering government appeals to hand in their weapons, including John Hart, a farmer in the North Island district of Masterton.

Hart said it was an easy decision for him to hand in his semi-automatic and tweeted that "on the farm they are a useful tool in some circumstances, but my convenience doesn't outweigh the risk of misuse. We don't need these in our country".

The tweet drew a barrage of derogatory messages to his Facebook account - most apparently from the US, where the pro-gun lobby is powerful and vociferous.

Hart deleted the messages but posted online: "A warm kia ora to all my new American Facebook friends." "I'm not familiar with your local customs, but I assume 'Cuck' is a traditional greeting," he said of the insult, short for "cuckold" frequently used by far-right pundits.

Police said they did not have data available on the number of weapons handed in since Friday.

But they issued a statement saying that "due to heightened security and the current environment, we would ask that people please call us first before attempting to surrender a firearm."

Ardern has said that details of the government's proposed law changes on gun ownership will be announced by next week, but she indicated that gun buybacks and a ban on some semi-automatic rifles were under consideration.

"As the Cabinet, we were absolutely unified and very clear: the terror attack in Christchurch on Friday was the worst act of terrorism on our shores, it was in fact one of the worst globally in recent times, it has exposed a range of weaknesses in New Zealand's gun laws," she said.