A child places flower bouquet at a makeshift memorial.

New Zealand Prime Minister Jacinda Ardern vowed 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."