Online platforms must act now to remove violent content viewed by the Southport killer to prevent further attacks, Chancellor Rachel Reeves has told the BBC.

Her comments on Sunday with Laura Kuenssberg come after the home secretary wrote to X, Meta, TikTok, Google and YouTube saying the ease of access to violent material was unacceptable.

The 18-year-old was sentenced to a minimum of 52 years in jail last week for murdering three young girls and attempting to murder 10 other people, including eight children.

Conservative leader Kemi Badenoch told the same programme that she believed that a lack of integration into society had played a role in the crimes committed by Rudakubana.

The government has announced a public inquiry will take place into the missed opportunities to stop him.

Alice da Silva Aguiar, nine, Elsie Dot Stancombe, seven, and six-year-old Bebe King were killed in the attack at a Taylor Swift-themed dance and yoga workshop during their summer holidays.

Their murderer had been known to police, anti-extremism authorities and other public agencies.

There had only been limited intervention and the government has said there were missed opportunities, with Prime Minister Sir Keir Starmer saying the state had failed.

Searches of the killer’s home uncovered material which suggested an obsession with violence, including the academic study of an al-Qaeda training manual downloaded from the internet.

Reeves told the BBC’s Sunday with Laura Kuenssberg: “It is totally unacceptable the fact that the killer, before he went on to commit those horrific crimes, was able to access – really easily – on some of the online platforms such hateful material,” she said.

“Those companies have got a moral responsibility to take that content down and make it harder for people to access it.

“Already in some countries around the world including Australia, the companies have taken it down. So they can do that.”

In the home secretary’s letter, co-written with Technology Secretary Peter Kyle, Home Secretary Yvette Cooper said that, while possession of the al-Qaeda document was illegal under existing anti-terror laws, Rudakubana had been “able to easily obtain access” to it.

Before leaving home to carry out the attack, he also watched graphic footage of a knife attack on Australian bishop Mari Emmanuel that had taken place a few months earlier.

Cooper noted the video of the attack had been removed in Australia but could still be accessed in the UK, adding the Southport attack had “laid bare the potential consequences of failing to act on such content”.

Reeves said the government’s online safety bill, which becomes law in March, can order the removal of violent and hateful material.

“Let’s not wait until then – we don’t need legislation to stop this from happening. These companies can, and they should, take that material down now,” she said.

She said her “heart goes out” to the families who lost their daughters, along with the children who “will forever remember the scenes they saw unfold”.

The chancellor added that lessons needed to be learned on what wrong and why such an “evil man” was not dealt with sooner.

The government also said on Sunday that stricter age checks on the sale of knives online would be introduced.

People will have to submit photo ID when they order an item and again when it is delivered, and it will be illegal to leave a package containing a knife on a doorstep if no one is in to collect it.

Starmer promised urgent action on the sale of knives to under-18s after the attack, saying it was “shockingly easy” to buy them. Rudakubana had bought the knife used in the attack on Amazon.

Badenoch told Laura Kuenssberg that there are “a lot of people” like Rudakubana who “despite being here from childhood or born here, they’re not integrating into the rest of society”.

“They hate their country,” she said. “And they are being told that everything about the UK is terrible.

“He had materials about white genocide.

“If you are being inculcated in hate, you are not integrating well. And there is so much that we can do across the board. Not just on religious extremism but also just extremism across the board.”

Pressed by Laura Kuenssberg on what evidence there was that the crimes were linked to integration, as the killer had been born in the UK, Badenoch said it was “one of the elements”. She said the evidence was her own experience with a similar background to Rudakubana as an African Christian.

Badenoch added that “the effort we make to make people feel a part of the whole is very limited and it shouldn’t just be government, it should be the whole of society”, with too many groups becoming insular and segregated.

She said the incident had affected her “really deeply” as her two daughters also love Taylor Swift. “When it happened, I could just imagine it being them,” she said.