Social media companies will face “very significant changes” as new legal safeguarding rules are set to come into force early next year.

The Chief Executive of Ofcom, Dame Melanie Dawes, told BBC Radio 5 Live that companies could face fines from the regulator if they did not comply with the new Online Safety Act.

Social networking services such as Facebook, Instagram and Whatsapp will have three months from when the guidance is finalised to carry out risk assessments and make relevant changes to safeguard users.

Dame Melanie said changes could include allowing people to take themselves out of group chats, without anyone else being able to see they had left.

“Young people should be able to take themselves out of group chats that they know are toxic for them, without everybody being able to see and that’s one of the things that we are going to be expecting to see change from social media and messaging services,” she said.

Dame Melanie also said it was the responsibility of the firms – not parents or children – to make sure people were safe online.

Ofcom has been putting together codes of practice since the Online Safety Act became law just under a year ago, to protect children from some legal but harmful material.

Platforms will also need to show they are committed to removing illegal content including child sexual abuse, promotion of self-harm and animal cruelty.

“It’s definitely not just a paper exercise,” said Dame Melanie. “We are very clear that the first step that any responsible company needs to take, is to actually access risks that they’ve never accessed before.”

She added that companies needed to be “honest and transparent” about what their “services are actually exposing their users to”.

“If we don’t think they’ve done that job well enough, we can take enforcement action, simply against that failure.”

Ofcom has already been in close contact with social networking services and Dame Melanie said when the new legal safeguards became enforceable the regulator would be “ready to go”.

She added: “We know that some of them are preparing but we are expecting very significant changes. ”