Prime Minister Jacinda Ardern led an estimated 5,000 people standing quietly at Hagley Park in front of the Al Noor mosque, where most of the victims died.

"New Zealand mourns with you. We are one," she said in a short speech, followed by two minutes of silence.

Most victims of New Zealand's worst mass shooting were migrants or refugees from countries such as Pakistan, India, Malaysia, Indonesia, Turkey, Somalia, Afghanistan and Bangladesh.

"We are broken-hearted, but we are not broken. We are alive, we are together, we are determined to not let anyone divide us," Imam Gamal Fouda told the gathered crowd, many wearing headscarves in support of the grieving Muslim community.

"To the families of the victims, your loved ones did not die in vain. Their blood has watered the seeds of hope," he said in prayers broadcast nationally.

Ardern, who swiftly denounced the attack as terrorism, announced a ban on military-style semi-automatic and assault rifles under tough new gun laws on Thursday.

Australian Brenton Tarrant, a suspected white supremacist, has been charged following the Christchurch attack and was remanded without a plea.

Tarrant is due back in court on 5 April, when police said he was likely to face more charges.

Burials of the victims begun on Wednesday, with a final mass burial expected after prayers on Friday.

Reuters/eNCA