Social media companies “need to take some responsibility” for speculation in the aftermath of the Southport attack, Home Secretary Yvette Cooper has said.

The senior Cabinet Office minister reminded social media users the case, in which three girls were killed at a Taylor Swift-themed holiday club, was “about children and their families who will be grieving”.

Ms Cooper’s intervention aimed at quelling social media rumours came after Downing Street urged the public to avoid “unhelpful” speculation about the attack, amid concerns that misreporting online could inflame community tensions.

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Home Secretary Yvette Cooper looks at tributes near the scene in Hart Street where three children died and nine were injured in a knife attack (James Speakman/PA)

The unnamed 17-year-old suspect is from Wales, Merseyside Police has said, but false claims that he was an asylum seeker who had arrived in the UK by boat have spread online.

The Home Secretary told the Commons: “There will be wider questions for other days, but the most important thing is that every one of us supports the police in their investigation now.

“I agree with (shadow home secretary James Cleverly) too about the responsibility on social media companies, because we do need to recognise there are things that are taking place on social media that go against their terms and conditions, and their commitments as well. They need to take some responsibility for that.

“Above all, this is about young children. This is about children and their families who will be grieving, and the many other children who were involved yesterday who will be facing great trauma as well.”

Her counterpart Mr Cleverly called for people not to “get involved in the grief of others” by sharing misinformation relating to the Southport attack on social media.

“Enough people are already distressed without their distress being amplified by speculation and gossip online,” he added.

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Prime Minister Sir Keir Starmer is seen carrying a floral tribute (James Speakman/PA)

The force is now understood to be monitoring a potential far-right rally in the area.

Asked whether the Prime Minister would appeal for calm if such an event were being planned, Sir Keir Starmer’s official spokesman said: “Of course, people should listen the police, they should not do anything that is going to make the police’s job harder to manage the situation, to conduct their investigations.

“It is unhelpful to speculate on things like the motive and the circumstance around this.”

It comes as Alice Dasilva Aguiar, nine, Bebe King, six, and Elsie Dot Stancombe, seven, were named as the three girls fatally stabbed in the incident on Monday.

Eight other children suffered stab wounds and five are in a critical condition, alongside two adults who were also critically injured, police said.

A 17-year-old boy, who cannot be named for legal reasons, remains in custody accused of murder and attempted murder following the attack at the dance studio in Hart Street.

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Bebe King, Elsie Dot Stancombe and Alice Dasilva Aguiar were fatally stabbed in the attack (Family Handouts/PA)

Police said a name shared on social media in connection with the suspect is “incorrect”, adding: “We would urge people not to speculate on details of the incident while the investigation is ongoing.”

Sir Keir visited the seaside town on Tuesday and thanked emergency service workers, telling them: “I hope you feel proud of the part that you played in the most difficult circumstances, to do what you could for those young lives.”

He laid down his wreath and stood momentarily in silence, but more than one person shouted: “How many more Starmer? When are you going to do something?”

A third man shouted “get the truth out!” while the Chief Constable was asked why the alleged attacker had not been named, and if he was on a “watch list”.

Police have said that, although the motive for the attack is unclear, it is not believed to be terror-related.

The force said the suspect, who was born in Cardiff, is from the village of Banks, just outside Southport, and a road in the area was cordoned off by detectives on Monday afternoon.