Molly Russell's father has accused the Government of "watering down" a legal crackdown on harmful online content.
Ian Russell, whose 14-year-old daughter took her own life after viewing self harm posts, said it was "very hard to understand" why social media firms won't be ordered to remove "legal but harmful" content.
The Government is overhauling its proposed Online Safety Bill to force tech giants to improve protections for children.
But ministers have ditched plans to outlaw the availability of material which is not illegal but could be deemed harmful after pressure from Tory MPs and campaigners.
Former Tory Tech Minister Lord Bethell branded the legislation "weak, weak, weak".
Culture Secretary Michelle Donelan insisted nothing was being watered down - and said that the content Molly saw would not be available under the new laws.
Ms Donelan decided to go through the bill again when she was appointed in September, with new amendments added today.
It previously had a section which required "the largest, highest-risk platforms" like Facebook, Instagram and YouTube to tackle some legal but harmful material accessed by adults.
This would have meant tech giants had to stop people being exposed to content like self-harm and eating disorder posts.
Instead, firms are now being told to introduce a system allowing users more control to filter out harmful content.
Platforms will have to remove illegal content, as well as take down any material that is in breach of its own terms of service.
Other updates will include requiring tech firms to show how they enforce user age limits, to publish summaries of risk assessments in regard to potential harm to children on their sites and declare details of enforcement action taken against them by watchdog Ofcom.
Mr Russell said he was relieved that the bill was moving forward after long delays but told the BBC : "I think the most harmful content to [Molly] was content that could be described as legal but harmful."
He added: "It is very hard to understand that something that was important as recently as July, when the bill would have had a full reading in the Commons and was included in the bill, this legal but harmful content, it is very hard to understand why that suddenly can't be there."
He added: "What we need is the assurance from the Secretary of State that this watering down of the bill by removing the legal but harmful content is at least boosted in other measures to make it safe for not just young people but for all of us to be online.
"I don't see how you can see the removal of a whole clause as anything other than a watering down."
But Ms Donelan said there would be no watering down of the bill when it came to children.
"Nothing is getting watered down or taken out when it comes to children," she said.
"I think it might be just misunderstanding what Ian has said on this. I've spoken to him even this morning.
So the legal but harmful aspect was pertaining to adults. Content that is harmful or could hurt children that is not illegal, so is legal, will still be removed under this version of the Bill.
"So the content that Molly Russell saw will not be allowed as a result of this Bill. And there will no longer be cases like that coming forward because we're preventing that from happening, and I want to be really clear on that."
But Julie Bentley, chief executive of Samaritans, described dropping the requirement to remove "legal but harmful" content as "a hugely backward step".
"Of course children should have the strongest protection but the damaging impact that this type of content has doesn't end on your 18th birthday," she said.
"Increasing the controls that people have is no replacement for holding sites to account through the law and this feels very much like the Government snatching defeat from the jaws of victory."
Shadow culture secretary Lucy Powell said it was a "major weakening" of the Bill,
She said: "Replacing the prevention of harm with an emphasis on free speech undermines the very purpose of this Bill, and will embolden abusers, Covid deniers, hoaxers, who will feel encouraged to thrive online."
The Samaritans is available 24/7 if you need to talk. You can contact them for free by calling 116 123, email jo@samaritans.org or head to the website to find your nearest branch. You matter.
