An 18-year-old New Zealand man accused of Facebook sharing a live-stream video of the Christchurch massacre that killed 50 people has been denied bail.

Police have said the teenager - who cannot yet be named - was not involved in the attack on two mosques.

Australian white supremacist Brenton Tarrant, 28, has been charged with the Friday afternoon murders.

The accused teenage Facebook poster appeared in Christchurch District Court on Monday and was granted an interim name suppression order, but he was denied bail by Judge Stephen O'Driscoll.

The young man has also been charged with allegedly posting to social media a photograph of one of the South Island mosques being attacked with the message 'target acquired' along with other chat messages 'inciting extreme violence'.

New Zealand Prime Minister Jacinda Ardern has also confirmed she would move to tighten national gun laws, following one of the world's worst peacetime shooting massacres in history.

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An 18-year-old New Zealand man (pictured) was refused bail in Christchurch District Court on Monday

Police allege the teenager shared a livestream of a mass shooting across two mosques. Pictured: Armed officers patrol a cemetery near Muslim graves in Christchurch

The details behind the alleged Facebook poster's bail decision cannot be published.

He will reappear in court in April. If found guilty, he could face up to 14 years' jail.

Facebook earlier said it had taken down 1.5 million copies of footage of the shooting that had been livestreamed by Tarrant in the 24 hours after the carnage.

Authorities and telecommunications companies last week also scrambled to have the videos taken down and urged the public not to share them.

Ms Ardern said she had contacted Facebook's chief operating officer Sheryl Sandberg to voice her concerns about the social media giant's sharing of extremist live-streaming material.

New Zealand Prime Minister Jacinda Ardern has also confirmed she would move to tighten national gun laws, following the world's second worst peacetime shooting massacre in history

'I haven't spoken to her directly but she has reached out, an acknowledgment of what has occurred here in New Zealand,' she told reporters on Monday.

New Zealand gun laws Appliants for a gun owner's licence in New Zealand are not legally required to establish a genuine reason to possess a standard hunting or sports shooting firearm, but specific reasoning is required for pistols and Military Style Semi-Automatic weapons. That reason could be pest control. There's no restriction on the number of guns or quantity of ammunition a licensed gun owner can have. An applicant for a firearm licence in New Zealand must pass a background check which considers criminal, mental health, medical, addiction and domestic violence. Third-party character references are required. Authorities are required to interview an applicant's partner or ex-partner or next of kin before issuing a gun licence. Gun owners must re-apply and re-qualify every 10 years. An A category rifle, which requires only a standard licence, can legally carry a seven-round magazine. This weapon can be illegally converted into a semi-automatic weapon if that magazine is replaced with, say, a 30-round magazine and a pistol grip added to the stock so gunfire can be sprayed from the hip. Sources: GunPolicy.org and its founding director, Associate Professor Philip Alpers of Sydney University Advertisement

'This is an issue that I will look to be discussing directly with Facebook'.

The New Zealand Prime Minister also confirmed she would push to reform the nation's gun laws, which haven't changed since 1992.

'To make our community safer, the time to act is now,' she told reporters on Monday.

New Zealand's cabinet has agreed in-principle to a range of gun reforms, but Ms Ardern declined to provide more detail at this stage.

The proposed changes could be announced before cabinet meets again next week.

Semi-automatic assault rifles are expected to be banned in New Zealand, and gun owners are likely to face stricter registration criteria.

'There are details to work through,' Ms Ardern said.

'These aren't simple areas of law, so that's simply what we'll be taking the time to get right.'

Deputy Prime Minister Winston Peters, who heads the conservative New Zealand First party, endorsed the plan.

'At 1pm on the 15th of March our world changed forever, and so will our gun laws,' Mr Peters said.

New Zealand amended its gun laws in 1992, after the Aramoana massacre of November 1990, which saw 13 people shot dead in a small township near Dunedin, following a neighbourhood dispute.

Background checks and special permits were introduced 26 years ago, however New Zealand lacks a national gun registry.

Police also allege the 18-year-old (not pictured) posted a photograph of one of the mosques attacked with the message 'target acquired'. A youth mourning the attack is pictured above

The Christchurch shooting was also New Zealand's first mass shooting since 1994.

New Zealand's gun lobby thwarted attempts to reform gun laws in 1999, 2005, 2012 and 2017.

Australia banned automatic and semi-automatic assault rifles following the 1996 Port Arthur massacre in Tasmania, where 35 people were killed.

The death toll in Christchurch, so far, is second only to the Las Vegas carnage of October 2017 which saw 58 people shot dead in the United States, when it comes to firearm-only atrocities in a Western nation involving a lone gunman.

Far-right Norwegian terrorist Anders Breivik killed more people in July 2011, but he had also used an explosive device before shooting dead 69 participants of a Workers Youth League summer camp on the island of Utoya.