NI parents have been warned to monitor children's online activity more closely during the Covid-19 lockdown.
Safeguarding body Ineqe has been contacted by several schools which have expressed concern about "online risks".
In the past week, one south Belfast primary school alerted parents about children accessing an adult chat room.
In a text message seen by BBC News NI, the school said the site was "highly inappropriate and dangerous".
It appealed to parents to "check your child's browsing history on their phones and laptops this evening and very regularly from now".
The Department of Education has launched an app to enable children and young people to access advice on a range of digital issues, including safety on social media platforms, bullying, sexting and online challenges.
The Safer Schools NI App was provided to the department for free by Ineqe, which said that because the news agenda has been focused on various issues around Covid-19 since the lockdown six weeks ago, the online threat to children learning at home has gone largely unreported.
'Kids get bored and curious'
Colin Stitt of Ineqe said "the distraction of the Covid-19 pandemic" has "blunted the urgent calls to address the increased risk to NI children online".
He said that in recent weeks, his organisation had received inquiries from various NI schools expressing concern about safeguarding and child protection issues and requesting the app.
He said the adult chat room mentioned by the south Belfast school is one Ineqe has been aware of for some time, and that it was, unfortunately, not an isolated case.
"Kids are more bored at home, they get curious, they look online and when they find something, they share it with their friends.
"Every school has different issues with digital safeguarding.
"Situations like this can create opportunities for predators and they'll exploit that," he said.
"We don't want to scaremonger, but that shouldn't be taken lightly."
In terms of advice for parents who want to raise the issue with children, he said the app gives tips and advice on how to get answers without causing tension.
"Open questions help keep conversations open and clear.
"Ask 'have you heard of this new app', rather than 'do you use this app'?
"Use these conversations to talk about staying safe and exploring what a child would do if they needed help - who could they talk to?
"You also need to agree on boundaries and applying safety settings together, depending on the age and understanding.
"We want to put the tools into the parents and grandparents hands to deal with this very real problem."
Ineque Chief Executive Jim Gamble said that because of lockdown, "children are spending more time online than ever before interacting with their real friends, friends of their friends (who they don't really know) and absolute strangers".
He added: "It's important not to create a culture of fear that there is a paedophile in every virtual space, but the current reality is most sex offenders are sitting at home, and most will have a computer."
Educate about online threats
Meanwhile, the principal of a County Down primary praised the south Belfast school for its "vigilance".
Kevin O'Neill of St Colman's Primary said online safety was "a huge concern" for principals across Northern Ireland.
"That school is clearly monitoring activity closely and has displayed a model response," he said.
St Colman's has previously worked closely with the PSNI and safeguarding bodies to educate children about online threats.
Mr O'Neill said the danger is even greater now that children are spending so much time online.
"We're really worried about the impact of this on our pupils - their world has shrunk. Their living room is now their classroom.
"Before, in their schools, their use of the internet would have been very closely monitored. Now, in many cases, it's not, and that's a concern.
"We would appeal strongly to all parents to keep an eye, without being intrusive, on what their children are viewing online. Kids are bored at home, but predators know that and they will exploit it."
The National Crime Agency (NCA) estimates that at least 300,000 individuals pose a sexual threat to children, with some discussing opportunities to abuse children in chat forums.
You can find information about how to download and use the app on the Ineqe website.