A headteacher has said pupils should not use the video conferencing app Zoom after trolls hacked into a school leaders’ meeting and shared “triple XXX” rated pornography.

The conference on coronavirus, which involved roughly 160 heads and academy chiefs, was “zoombombed” by internet users, who posted content that “would have broken every safeguarding issue going” in a virtual classroom, according to headteacher Chris Dyson.

Mr Dyson, who is head of Parklands Primary in Leeds, said trolls shared “triple XXX pornography” after gaining access to the video conference through an unprotected link shared on social media.

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He said this should be a “warning” to schools that children must not use Zoom.

The conference was part of a series of “webinars” organised by headteacher Simon Kidwell, where school leaders can share their response to the coronavirus.

Mr Kidwell said extra security measures have now been put in place to prevent future intrusions.

Mr Dyson told Tes: “There were 160 big playing headteachers and CEOs on our Zoom chat this morning when we got hijacked.

“The meeting was shared freely over Twitter and wasn’t password protected (so huge lessons learnt and a warning for schools with children NOT to be using it).

“The hijacking was in the form of triple XXX pornography. There were some very, very, very distressed people on the thread.

“If it had been a Zoom classroom it would have broken every safeguarding issue going, so in a way I am glad it happened to us.

“It’s important that we get this message out to schools who are setting up Zoom classrooms.”

Mr Kidwell added: “School leaders have been hosting daily webinars sharing their response to the coronavirus. We have been sharing links on Twitter.

“Today we had a number of non-teachers join the meeting posting inappropriate comments in the chat.

“We ended the chat immediately when a graphic image was shared.”

In an email sent to participants, Mr Kidwell said: “Apologies over the hacking that went on in our webinar today and as a result we will be adding some security measures to our future meetings.”

These include using a virtual “waiting room”, so hosts can verify attendees’ identities before allowing access to the webinars; disabling the screen share function; adding password protection; and creating a new meeting ID for every session.

The news comes just one day after an online seminar providing legal advice to teachers was flooded with abusive messages and foul language in a nasty case of “zoombombing”.

Tes has also published a warning to teachers about the risks associated with hosting lessons on Zoom.