23/05/2017 22:06 BST | Updated 24/05/2017 10:55 BST

Operation Temperer: Theresa May Says Military Poised To Patrol Streets As UK Terror Threat Level Raised To Critical

PM warns another attack considered imminent.

Britain has raised the terror threat level from severe to critical for first time since 2007 in the aftermath of the Manchester attack, Theresa May has said.

It is the first time the threat level has been raised to its highest since 2007. In an address to the nation, the Prime Minister said the increased threat level will see Operation Temperer enacted, which will mean up to 5,000 troops could be called on to take over armed police patrol duties under police command.

It is possible that there is a “wider group of individuals” were responsible for the Manchester explosion, she added.

The heightened concern followed 22 people being killed and 59 injured in the Manchester Arena suicide attack. 

British police identified the attacker as Manchester-born Salman Abedi, 22.

May said the move was a “proportionate and sensible response” as she condemned the “callous and the cowardly” Monday attack.

May said the measures include replacing police officers who now guard “key sites” with members of the military operating under police command.

She added the public “might also see military personnel deployed at certain events such as concerts and sports matches.”

May said:

“In my statement earlier today I said police and security services needed ton investigate whether or not Abedi was acting alone. Those investigations continue. But the work undertaken throughout the day has revealed that it is a possibility we cannot ignore that there is a wider group of individuals linked to this attack

“This morning I said that the Joint Terrorism Analysis Centre (JTAC), the independent organisation responsible for setting the threat level on the basis of the intelligence available, was keeping the threat level under constant review.

“It has now concluded on the basis of today’s investigations that the threat level should be increased for the time being, from severe to critical.

“This means that their assessment is not only that an attack remains highly likely but that a further attack may be imminent.

“The change in the threat level means there will be additional resources and support made available to the police as they work to keep us all safe.

“As a result of JTAC’s decision, the police has asked for authorisation from the Secretary of State for Defence to deploy a number of armed military personnel in support of their armed officers.

“His request is part of a well-established plan known as Operation Temperer in which the armed forces and the police involved are well-trained and well-prepared to work in this kind of environment

“The Secretary of State for Defence has approved this request and Operation Temperer is now in force.

“This means that armed officers responsible for guarding key sites will be replaced by members of the armed forces which will allow the police to significantly increase the number of officers on patrol in key locations.”

She added:

“You might also see military personnel deployed at certain events such as concerts concerts and sports matches helping police to keep the public safe. Military personnel will be under the authority of police.

“I do not want the public to feel unduly alarmed. We have faced a serious terrorist threat in our country for many years and the operational response I have just outlined is a proportionate and sensible response to the threat our security experts judge we face.”

Earlier in the evening, thousands of people gathered in the centre of Manchester in a show of defiance, declaring they will not be afraid in the wake of the terror attack.

Crowds spilled from Albert Square on to nearby roads, standing together in an act of solidarity, and showing that the city “always pulls together”.

The crowd erupted into applause as the vigil began, and Lord Mayor of Manchester Eddy Newman said it was a chance to “express solidarity” with the victims.

Poet Tony Walsh performed a touching ode to Manchester called This Is The Place, which sparked ripples of laughter, lightening the mood as the sun beamed on the Town Hall.

He described the city as “ace”, hailed its “brilliant music” and said Mancunians “make people laugh” and “welcome”.

In a poignant moment he referred to the “Mancunian way to survive” and “northern grit”, and said: “In the face of a challenge we always stand tall.” 

Abedi’s attack at a concert by US pop star Ariana Grande left 22 people dead, including an eight-year-old girl, and dozens injured.

Abedi, believed to have been born in Manchester and of Libyan descent, studied business at Salford University but dropped out before completing his degree.

The 23-year-old is thought to have attended the Manchester Islamic Centre, also known as Didsbury Mosque, along with his parents and siblings.

The party leaders’ campaigns for the June 8 General Election will remain suspended on Wednesday following the Manchester Arena terrorist attack.

May, who visited Manchester and chaired two meetings of the emergency Cobra committee on Tuesday, will continue handling the response to the atrocity.

The campaigns of Labour leader Jeremy Corbyn and Liberal Democrat counterpart Tim Farron, who both attended the vigil in Manchester after the attack, will also remain paused.