Justice officials feared children would be increasingly subjected to internet predators during lockdown, as a result of spending more time online.
Documents released this afternoon by the Joint Venture on Family Violence and Sexual Violence (JV) say "additional risks" also included young people accessing or viewing inappropriate content such as online pornography.
Data from Pornhub shows a massive spike in traffic the day New Zealand went into lockdown.
And the officials were worried about children being particularly vulnerable to under-reported abuse, and to witnessing violence at home, as abusive behaviours escalated in isolation.
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To try and combat such abuse, the Government put an increased focus on prevention and early intervention, including messages about promoting the right behaviours and supporting people to ask for help as well as for people to provide help.
However, it still expected family and sexual violence to rise, including as lockdown restrictions eased - but that it would go unreported for a time.
"The JV hears that people in violent situations may not be able to safely access helplines," the paper said.
"There is also greater stress on families as the lockdown affects people's mental health and economic circumstances, which increases the risk of violence over the coming weeks, and this increase in risk may continue after the lockdown period while people continue to adjust to the social and economic impact of Covid-19."
It was particularly concerned about the under-reporting of child abuse, about abuse of older people, and how withdrawal from alcohol and other drugs could lead to an escalation in family and sexual violence.
"There is an increased probability that children and young people will take additional risks when online for longer periods at home, like accessing or viewing inappropriate content such as online pornography," it said.
"The largest online pornography site [Pornhub] has shown an increase in use in New Zealand, and other countries, as we moved into alert level 4. This use is up over the same period last year."
In a briefing on online harms from the Minister for Internal Affairs Tracey Martin, a graph from Pornhub showed a 20.6 per cent increase in their New Zealand traffic when the country moved to alert level 4 on March 25.
Traffic dropped back to a 4.8 per cent increase by March 29 but then crept back up to 15.8 per cent on April 2.
Documents noted a raft of preventative actions recommended by the agencies involved in the Joint Venture, which span social and crime departments across Government.
These included spending $12 million to support family and sexual violence services to stay open, to prove accommodation for those in need and to provide food and other essentials, like phone data.
It also noted that the Department of Corrections has already committed to funding community programme providers to enable them to continue supporting people serving sentences for harmful sexual behaviour against children and for family violence, as a prevention measure.
It would also build a data dashboard to understand how Covid-19 was affecting the sexual and family violence sector.
"The dashboard will evolve as we obtain more data and information and start to identify trends over time. Its value will extend beyond the current pandemic period as it will continue to provide an evidence base for the work of the JV."
Campaign to make online safe for kids
The briefing from Martin also showed children were experiencing online threats and harm by spending more time on Netflix, YouTube, online games and social media.
This increased the risk of young people experiencing:
• Mental and psychological harm from seeing inappropriate content (from porn to age-restricted films and illegal content);
• Online bullying and harassment on social media sites and forums;
• Online grooming and other malicious activity that can lead to sexual exploitation and abuse.
Martin proposed a $1.5m cross-government public campaign to provide parents and caregivers with information to help them create a safe online environment during the lockdown. Cabinet agreed.