A Northern Ireland principal has claimed his school was told to stop using video-conferencing app Zoom due to security concerns.
BBC Radio Ulster's Nolan Show reported that the school was advised by a Department of Education official to stop using Zoom and other video-conferencing services as security could not be guaranteed.
It comes after reports of chats on Zoom and similar services being hacked with explicit material being displayed.
Many schools are relying on video-conferencing to allow them to continue teaching from home during the coronavirus pandemic.
The name of the affected school or its principal were not disclosed. Zoom sessions between teachers and pupils at the school have now been cancelled.
The Department of Education said they had no knowledge of the incident, but would "urgently investigate" any concerns.
A Zoom spokesperson said the company was "deeply upset" to hear of the incident and had recently introduced several measures to increase security.
In documentation seen by the BBC parents were warned that the school "strongly advised that we are unable to video conference with pupils for various significant child protection reasons".
"We await information from the Department of Education as to how schools might safely use this function".
NASUWT national official Justin McCamphill said the organisation "knew very little" about the incident, but were aware that Zoom was having security issues.
He acknowledged that efforts had been made to tighten up security on the program.
"If these things are still happening the message to schools should be stop using Zoom until these issues are resolved," Mr McCamphill told the Nolan Show.
The union official said that as far as he knew there had not been official guidance from the Department for Education on Zoom and similar services.
He said that NASUWT had produced advice for members that they "only should be using school based platforms, rather than commercial platforms".
"Our view is that if this is something that individual teachers wish to do, it should be on a department approved system," Mr McCamphill said.
A spokesperson for the Department of Education said: “The Department expects schools to make provision for the children of key workers and vulnerable children and for remote learning, whether through the use of technologies or hard copy packs or a blend of both.
“When schools are using technology, the safety and security of pupils must be the primary concern and for this reason schools continue to be encouraged to use the secure EA C2K services when setting up online learning opportunities and communicating with young people while they are home learning.
"EA C2K currently offer two video conferencing solutions within the secure education cloud network, Education Network NI and the Department recommends that schools make use of these.
“The EA C2K service desk is available to continue to support school staff with technical and safeguarding advice around online learning during this challenging time.”
The Zoom spokesperson said the company had a number of measures in place to help schools.
“Zoom strongly condemns such behaviour and recently updated several features to help our users more easily protect their meetings," the spokesperson said.
"In addition to our offering of training, tutorials and webinars, Outschool and Nearpod are providing additional resources about online learning for educators.
"Zoom is committed to providing educators with the tools and resources they need on a safe and secure platform, and we are continuing to engage with all of our users on how they can best use Zoom and protect their meetings.”
A spokesperson for the Education Authority (EA) said: “We recognise the significant contribution of schools, as they continue to go above and beyond to provide both academic and pastoral care to children, young people and families during this challenging period and we are committed to supporting schools in their efforts to deliver effective home teaching and learning solutions.
"Our C2K network, which provides a range of online learning resources, currently offers two secure video conferencing solutions.
"Schools are encouraged to utilise C2K’s secure platforms and EA staff are available to provide professional training and safeguarding advice, upon request.
"We will continue to work closely with school leaders and further information on learning support is available at www.eani.org.uk.”