Online firms have been given a three-month period from today to put in place a robust system to tackle illegal activity on their platforms or face financial punishments from the regulator.

As part of the UK’s Online Safety Act (OSA), Ofcom has published the first edition of its codes of practice and guidance on tackling illegal harms, which includes terror, hate, fraud, child sexual abuse and assisting or encouraging suicide.

The government finally signed the OSA into law last year after a series of lengthy delays. In its original form, the bill gave regulators wide-ranging powers to sanction digital and social media companies such as Google, Facebook, Twitter and TikTok, although later revisions watered down some of the proposals.

As well as social media firms, search engines, messaging, gaming and dating apps and pornography sites will fall under the remit of the OSA.

Ofcom said its measures are “explicitly designed” to tackle online grooming. It will mean that on platforms where users...