Armed police on streets but '˜no specific threat'

Mr Wallace spoke as visitors to Blackpool were told to expect to see armed officers on the street this bank holiday weekend.

Key resort attractions have also stepped up security following Monday’s suicide bomb attack in Manchester and the raising of the UK’s threat level to ‘critical’, which means an attack may happen imminently. There is no suggestion Blackpool is a target.

Whitehall sources revealed that security services are managing around 500 active investigations relating to 3,000 people of interest.

Salman Abedi, who carried out the atrocity at the Manchester Arena, which killed 22 people including South Shore Academy receptionist and mum-of-three Jane Tweddle, 51, was known to security forces before his deadly assault. Mr Wallace said: “All those people are in the mix and they have to be looked at.

“And then below the 3,000 is another 12,000 people who have in the past come to our attention and haven’t necessarily shown signs of doing anything at all, or no longer pose a risk.

“All of that is predominately underpinned by intelligence, which as I’m sure you will understand and the courts certainly understand, unfortunately the hardest part is we’ve got to convert intelligence into evidence if we actually want to deprive people of their liberty or take certain steps.”

Eight suspects aged between 18 and 38 were yesterday in custody in connection with the Manchester bombing, counter-terror detectives said.

Greater Manchester Police provided the first full breakdown of arrests made in the huge investigation into whether a ‘network’ supported Abedi’s attack at Ariana Grande’s sell-out concert.

As well as those killed, 116 required hospital treatment. Some 66 were still being treated, with 23 in a critical condition, some of whom are children.

A 16-year-old boy arrested in Withington on Thursday and a 34-year-old woman arrested in Blackley on Wednesday have been released without charge.