Senior government officials knew weeks ago that terrorism charges could be brought against the Southport attacker

Downing Street has denied any government involvement in the timing of the announcement of the charges. A spokesman said: “No – charging and charging decisions are a matter for CPS to make.”

Ms Cooper warned against speculation about the case, adding: “The most important thing is justice for Bebe, Alice and Elsa and their devastated families, as well as all those affected by the attack, and no one should put that at risk.”

Jonathan Hall KC, an independent reviewer of terrorism legislation, said authorities should be more open with information on terrorism cases to avoid an “information gap” that could be exploited by people using social media.

Hall told BBC Radio 4’s Today programme: “The police and CPS are operationally independent and that is important. And if the police and the CPS say ‘we really don’t think it’s OK to put anything more into the public domain’, I think that should influence the government.

“On the other hand, I also think that the government must and will be aware that if there is an information gap, especially in the mainstream media, there will be other voices – especially on social media – who will try and fill it.

“I always tell the government… if there is information that you can provide, put it in the public domain and be careful not to fall into the trap of saying, ‘We can say zilch just because there are criminal proceedings.’

“Quite often a large amount of information can be published in the public domain and I think the police are trying to do that. “They now realize that simply saying ‘there is an allegation, we can’t say anything more’ is not enough at this point.”