Recovering addicts were left “devastated” after child abuse images flashed up during an online support group meeting.
Bristol-based Celebrate Recovery were using the video chat app Zoom and say the meeting was meant to be private.
Christy McMullen, who runs the group, suspects they were hacked and said the incident left him “in total shock”.
Avon and Somerset Police is investigating.
The 12 participants, who normally meet weekly at Hope Community Church in Hotwells, were about an hour into the meeting on Monday evening when it was disrupted and the abuse images appeared.
“I was in total shock,” Mr McMullen said. “It traumatised me to be honest.”
“Everyone is vulnerable in our group. We are all trying to get well, trying to move out of our bad thinking into good thinking, and then that was put on there. It absolutely devastated all of us.”
The group helps people with a variety of addictions.
‘Difficult to sleep’
Group member Phil, who did not want his surname published, added: “It made me feel sick in the stomach.
“Afterwards it was very difficult to get to sleep. I was mulling it over and thinking about it and couldn’t get it off my mind.”
Mr McMullen reported the incident to Avon and Somerset Police who said it was the first case of its kind in the Avon and Somerset area since the Coronavirus outbreak.
Other investigations are also under way after Zoom meetings were infiltrated by people sharing footage of children being sexually abused.
Meetings targeted included a UK legal education seminar and one in Belgium organised by the 40,000-strong Federation of Young European Greens.
Zoom has been approached for comment.
The company has previously apologised for security problems, saying it is working hard on improvements.