Ofcom has launched an investigation into whether the Telegram messaging platform is failing to prevent the sharing of child sexual abuse material (CSAM) under the UK’s Online Safety Act.

The communications regulator carried out an assessment and decided to launch an investigation after receiving evidence from the Canadian Centre for Child Protection that suggested child sexual abuse material was allegedly present and being shared on Telegram.

The investigation will examine whether Telegram is failing to restrict child sexual abuse material from its site and whether it has breached the UK Online Safety Act.

Suzanne Cater, the director of enforcement at Ofcom, said: “Child sexual exploitation and abuse causes devastating harm to victims, and making sure sites and apps tackle this is one of our highest priorities. It’s why we work so closely with partners in law enforcement and child protection organisations to identify where these harms are occurring and hold providers to account where they’re failing to meet their obligations.”

The Guardian identified 150 Telegram channels around the world, including the UK, where AI-generated deepfake nudes were being created and shared on the secure messaging app.

According to a report by AI Forensics, 24,671 Telegram users were identified as actively sharing non-consensual intimate images, including child sexual abuse material, in Italy and Spain. The investigation found that perpetrators were predominantly young heterosexual men and that content was often monetised through one-time fees or monthly subscriptions to channels.

Silvia Semenzin, a senior researcher at AI Forensics, said: “Regulators must act with urgency and courage, listening to survivors’ experiences and demands, and mandate Telegram to cooperate with law enforcement and civil society, and to remove channels and groups sharing illegal content immediately and permanently – not after prolonged negotiation at victims’ expense.”

The UK Online Safety Act requires providers of user-to-user services – where people encounter content that has been uploaded by other users – to restrict illegal content.

Ofcom can impose fines of up to £18m or 10% of the company’s worldwide revenue. In the most extreme cases, a court could require advertisers or payment providers to withdraw their services from a platform, or require internet providers to block access to the site in the UK.

Ofcom has also opened investigations into Teen Chat and Chat Avenue to examine whether the chatroom providers are protecting children from grooming, after child protection agencies raised concerns about the platforms.

Previous enforcement proceedings launched by Ofcom to tackle child sexual abuse material on filesharing services led to hash-matching techniques – an automated tool that can detect and remove flagged content – being implemented on Pixeldrain. Yolovit, a filesharing service, was made unavailable in the UK after failing to comply with the OSA.

A Telegram spokesperson said: “Telegram categorically denies Ofcom’s accusations. Since 2018, Telegram has virtually eliminated the public spread of CSAM on its platform through world-class detection algorithms and cooperation with NGOs.

“We are surprised by this investigation and concerned that it may be part of a broader attack on online platforms that defend freedom of speech and the right to privacy.”