The death toll in the New Zealand mosque shootings rose to 50 on Sunday after police said they found another body at one of the mosques, while authorities worked to formally identify victims and release their bodies to families.

Australian Brenton Harrison Tarrant, 28, a suspected white supremacist, was charged with murder on Saturday. Tarrant was remanded without a plea and is due back in court on April 5 where police said he was likely to face further charges.

Friday's attack, which Prime Minister Jacinda Ardern labelled as "terrorism", was the worst ever peacetime mass killing in New Zealand and the country had raised its security threat level to the highest.

Footage of the attack on one of the mosques was broadcast live on Facebook, and a "manifesto" denouncing immigrants as "invaders" was also posted online via links to related social media accounts.

The bodies of the victims had not yet been released to families because investigations were ongoing, but police were working as quickly as they could to do that, Police Commissioner Mike Bush said at a media conference in Wellington.

It is customary in Islam to bury the dead within the 24 hours.

"We have to be absolutely clear on cause of death and confirm their identity before that can happen. But we are also aware of the cultural and religious needs, so we are doing that as quickly and sensitively as possible," Bush said.

Bush said the body of the 50th victim was found at the Al Noor mosque, where more than 40 people died after a gunman entered and shot randomly at people with a semi-automatic rifle with high-capacity magazines, before travelling to a second mosque.

"As of last night we were able to take all of the victims from both of those scenes. In doing so we were able to locate a further victim," he said.

Thirty-six people were still in Christchurch Hospital, with 11 being treated in intensive care, and one child moved to a dedicated children's hospital in Auckland.

At a roadblock outside the Al Noor mosque on Sunday, about 40 people were standing in silence near scores of bunches of flowers. Police with gloves and metal detectors combed the street and footpath.

Hero hailed

One man at the second mosque in the suburb of Linwood was hailed for distracting and confronting the shooter, preventing further deaths.

Abdul Aziz, 48, told local media he heard shooting and ran outside the mosque, shouting at the gunman and drawing him away from the building, the Newshub website reported.

Aziz, originally from Afghanistan, said he picked up one of the gunman's discarded weapons and threatened the man, who drove off.

Police then rammed the gunman's vehicle and arrested him.

"Those two police officers acted with absolute courage," Bush said. "They have prevented further deaths and risked their own lives to do so."

Church services for victims of the attack were held around the country, including at Christchurch's "Cardboard Cathedral", a temporary structure built after much of the central city was destroyed in a 2011 earthquake.

The majority of victims were migrants or refugees from countries such as Pakistan, India, Malaysia, Indonesia, Turkey, Somalia and Afghanistan. Muslims account for just over one percent of New Zealand's population.

Pakistan's High Commissioner said six citizens had been killed and three were missing.

Gun reform

Bush said police did not believe that three other people arrested on Friday were involved in the attack. Two men faced charges unrelated or "tangential" to the attack, while a woman had been released, he said.

Tarrant did not have a criminal history and was not on any watchlist in New Zealand or Australia.

In a manifesto circulating online, Tarrant described himself as "Just an ordinary White man, 28 years old" who used the spoils of cryptocurrency trading to finance extensive travels through Europe from 2016-2018.

Ardern said Tarrant was a licensed gun owner who allegedly used five weapons, including two semi-automatic weapons and two shotguns, which had been modified.

"I can tell you one thing right now, our gun laws will change," Ardern told reporters on Saturday, saying a ban on semi-automatic weapons would be considered.

New Zealand has tried in the past to tighten firearm laws, but a strong gun lobby and culture of hunting has stymied such efforts.

There are an estimated 1.5 million firearms in New Zealand, which has a population of only five million, but the country has had low levels of gun violence.

- Reuters