“Unhelpful” speculation about the deadly knife attack in Southport must be avoided while police continue to investigate, Downing Street has warned amid concerns that misreporting online could inflame community tensions.

Officers should be given the space to probe the case, in which three girls were killed at a Taylor Swift-themed holiday club, without people guessing at the possible motive or circumstances, Number 10 said.

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.

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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.

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Bebe King, Elsie Dot Stancombe and Alice Dasilva Aguiar (Family handouts/Merseyside Police)

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.

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.”

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Messages and floral tributes near the scene in Hart Street, Southport (James Speakman/PA)

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.