
Troops are to be deployed onto Britain's streets amid fears a further terror attack 'may be imminent', the Prime Minister has announced.

Theresa May revealed the move less than 24 hours after the bomb attack at a teen concert in Manchester, which left 22 dead and 59 injured.

The Prime Minister confirmed the identity of the Manchester suicide bomber as 22-year-old Salman Abedi, a Mancunian of Libyan descent.

But intelligence agencies fear he may not have acted alone - leaving open the possibility of an active Islamist terror cell on the loose.

Britain's Joint Terrorism Analysis Centre last night raised the terror threat level to 'critical', its highest level.

The threat level has only been raised to 'critical' twice since the system was introduced on August 1, 2006.

It came after the worst UK atrocity since 2005, when a nail bomber murdered 22 concert-goers as young as eight at an Ariana Grande concert.

Abedi, a Mancunian of Libyan descent, was the son of an airport security worker, MailOnline can reveal.

Police yesterday carried out a controlled explosion at the doorstep of his home during raids around the city. Forensics officers were seen emerging from the killer's property carrying a booklet called Know Your Chemicals.

Police also raided a house where Abedi's brother Ismail, lived and the 23-year-old was arrested outside a Morrison's in the Chorlton area of Manchester.

Eight of the 22 victims have been named as college student Georgina Callander, eight-year-old schoolgirl Saffie Roussos, 26-year-old John Atkinson, Kelly Brewster, 32, Megan Hurley, Alison Howe, 45, Lisa Lees, 43, and Olivia Campbell, 15.

Theresa May has said the terror threat level has been raised to 'critical' for the first time since 2007

This graphic shows the timeline of the horrifying night at the Manchester Arena which left 22 people dead

TERROR THREAT LEVEL RAISED TO 'CRITICAL' Just one week after its launch, the levels were raised to critical when police uncovered a plot to smuggle explosives on passenger jets travelling between the UK and US. There was a fresh state of heightened alert in June 2007 when a blazing car loaded with propane cannisters was driven into Glasgow Airport. Critical is the highest threat level under the system which is 'designed to give a broad indication of the likelihood of a terrorist attack'. Low means an attack is unlikely while moderate means an attack is possible, but not likely. Moving up the scale, substantial means an attack is a strong possibility while severe means an attack is highly likely. The highest level - critical - means an attack is expected imminently. The threat level for the UK from international terrorism is set by the Joint Terrorism Analysis Centre (JTAC). MI5 is responsible for setting the threat levels from Irish and other domestic terrorism both in Northern Ireland and in Great Britain. In reaching a judgement on the appropriate threat level in any given circumstance several factors need to be taken into account. These include judgements about the threat 'based on a wide range of information' including the nature of current terrorist activity and events in other countries. Advertisement

Security services are trying to establish whether Salman worked alone or was part of a wider network that helped him with the bomb.

A school friend told The Times that Abedi had returned to Libya in the past week.

The friend said: 'He went to Libya three weeks ago and came back recently, like days ago.'

On Monday evening he placed a suitcase on the ground in the foyer of the Manchester Arena moments before it detonated, according to CCTV footage recovered by detectives.

The Daily Mirror have also claimed an investigation is under way on his ties with fellow Mancunian Raphael Hostey, also known as Abu Qaqa al-Britani, a known Islamic State recruiter from the city.

Speaking inside Downing Street following a meeting of the emergency committee Cobra, Mrs May said: 'Earlier today I said the security services needed to investigate whether Abedi was working alone and these investigations continue.

'It is a possibility we cannot ignore that there is a wider group of individuals linked to this attack.

'The joint terrorist analysis centre has concluded 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 a further attack is imminent.'

It means armed soldiers will patrol key sites across the country, at sporting fixtures and musical events.

Undercover SAS troopers will join regular soldiers in Operation Temperer.

She added: 'We don't want the public to feel unduly alarmed. We've faced a serious terrorist threat in this country for many years.'

She said the response was 'proportionate and sensible'.

The Prime Minister said: 'The liberal pluralistic values of Britain will always prevail over the hateful ideology of the terrorists. They proved that cowardice will always be defeated by bravery.'

This picture shows where police carried out a series of raids across Manchester, including at the house of Salman Abedi and his 23-year-old brother Ismail who was arrested outside a Morrison's on Carlton Road

Mrs May closed her statement saying the spirit of Manchester and Britain as a whole showed the terrorists would not win, and branded atrocities such as last night's 'sick plots'.

She said: 'That's why the terrorists will never win, and we will prevail.'

Tonight's announcement comes after ISIS claimed responsibility for the worst terror attack Britain has seen since the 7/7 London bombings.

The suicide bomber, Salmon Abedi, was known to the security services but was not part of any active investigation or regarded as a high risk.

He died at the scene and police today carried out a controlled explosion at his home as chemical experts were seen outside with specialist instruments to check the property for traces of chemicals or explosives.

Casualties are stretchered out of the concert on Monday evening after a terror attack in the Ariana Grande concert

A girl is consoled after escaping the terror inside the Ariana Grande concert at Manchester Arena on Monday night

A girl, wrapped in a blanket, is led away from the arena following the terror attack in Manchester last night

This was the scene inside the Manchester Arena last night after the terror attack at the teen concert

This photo shows the aftermath of the suicide bomb which ripped through the foyer of the venue killing parents and children

The ambulance service warned people only to call 'for life-threatening emergencies' and said a 'large number of resources' were at the incident

Two women support each other as they walk away from the concert venue. The pink balloon being carried is a reminder of the huge number of children who attended the performance

Heavily-armed officers watch on as a colleague with a dog walks along the pavement following last night's attack

Born in Manchester on New Year's Eve 1994, the third of four children, his parents were Libyan refugees who came to the UK to escape the Gaddafi regime and his father is a suspected fighter who left the UK in 2011 to try to overthrow the Libyan leader.

His father, Ramadan Abedi, is a former airport security worker, MailOnline can reveal.

He emigrated to London with his wife Samia Tabbal, 50, before moving to the Fallowfield area of south Manchester where they settled in a housing association-owned home about two miles from the scene of Monday night's terror attack.

Footage emerged today of the moment armed anti-terror police raided Abedi's home in the Fallowfield area of Manchester

A forensics expert leaving Abedi's house this afternoon was seen holding a police issue book called 'Know Your Chemicals'

This was the 'Know Your Chemicals' book a police forensic investigator carried from Abedi's address in Elsmore Road

Security service personnel in camouflage were seen entering the property after police burst through the door today

A huge number of police - including armed officers - carried out a raid on a house in the Fallowfield area of the city today

Armed officers guard a second property raided by the police today in Carlton Road, Manchester. Police were last night also quizzing his brother Ismail, 23, on suspicion of involvement in the bombing

Friends and neighbour said Abedi appeared to be a normal football-mad teenager who was massive Manchester United fan and spent hours playing computer games on the PS4. He is said to have attended multiple schools including Manchester Claremont Primary School, Burnage Academy, William Hulme and Stretford Grammar School.

But everything changed in 2011 when his father abruptly left his job and home in the anonymous suburb to fight in Libya, leaving his family to fend for themselves, according to a local imam.

Abedi and his brothers appear to have followed in his footsteps by sharing stories of British jihadis fighting in Syria on social networks and even praying in the street.

The suicide bomber was heard chanting Islamic prayers in Arabic just weeks before the attack, a neighbour has revealed.

Lina Ahmed, 21, told MailOnline: 'They were a Libyan family. A couple of months ago he [Salman] was chanting the first kalma [Islamic prayer] really loudly in the street. He was chanting in Arabic. He was saying 'There is only one God and the prophet Mohammed is his messenger.'

A bloodied man with a bandage around his head stands outside the venue. He is covered with a foil blanket for warmth

Armed police officers stand next to a cordon outside Manchester Arena. There is a heavy police presence around the city

WHAT IS OPERATION TEMPERER? Documents uncovered by The Mail on Sunday in July 2015 revealed that the operation, codenamed Operation Temperer, would see 5,000 heavily armed troops deployed. The unprecedented operation would see troops guard key targets alongside armed police officers, providing 'protective security' against further attacks, while counter-terror experts and MI5 officers hunted down the plotters, it reported at the time. In measures announced by Mrs May last night, armed police officers responsible for duties such as guarding key sites will be replaced by members of the armed forces. This, she said, will allow the police to significantly increase the number of armed officers on patrol in key locations. At the time the documents emerged, Baroness Jones, who sits on London's Police and Crime Committee, said she was 'shocked' at the plans, saying: 'This would be unprecedented on mainland Britain.' And she expressed concern that the troops would not be sufficiently trained to protect civil liberties. The paper says up to 5,100 military personnel could be deployed 'based upon force assessments of how many military officers could augment armed police officers engaged in protective security duties'. Advertisement

Salman and his brother Ismail worshipped at Didsbury mosque, where their father is a well-known figure.

Ramadan is thought to be in Tripoli. His wife, Samia, is undestood to be in Manchester.

Some were shocked by Salman's involvement in the terror attack. One member of Manchester's Libyan community told The Guardian: 'Salman? I'm astonished by this. He was such a quiet boy, always very respectful towards me. His brother Ismail is outgoing, but Salman was very quiet. He is such an unlikely person to have done this.'

However others had a different recollection of the 22-year-old. Mohammed Saeed, the imam of Didsbury Mosque and Islamic Centre, said Salman Abedi had looked at him 'with hate' after he gave a sermon attacking ISIS and Ansar al-Sharia in Libya.

He said a friend was so concerned that he got his adult children to sit beside Salman Amedi in case he attacked the imam.

Police were last night also quizzing his brother Ismail, 23, on suspicion of involvement in the bombing.

The IT manager, who is married to a maths teacher, worked for Park Cake Bakeries in Oldham until January. It is believed that Ismail, who worked as a teaching assistant giving Arabic classes and IT support at Didsbury mosque Quran school, was once reported to a counter- terrorism unit after concerns were raised by members of the Muslim community.

Paramedics carrying rucksacks full of medical equipment walk along the pavement towards the Arena. Politicians were quick to praise the reaction of the emergency services

Witnesses described seeing crowds of people outside the concert hall on their phones trying to contact their parents

Leon Hall, who went to school with Abedi, told MailOnline he saw the killer last year and said he had grown a beard. He also said the jihadist was a keen Manchester United fan.

Mr Hall said: 'I saw him last year and he had a beard thing going on. We didn't speak but just nodded to each other. I don't remember seeing him with beard before.'

'He always had a bit of an attitude problem. I can't say I really liked the man.'

Mr Hall said Abedi lived in a housing association owned home about two miles from the scene of Monday night's terror attack.

Abedi's younger brother Hashim, now 20, has posted comments on ISIS-supporting sites. He showed an interest in Reyaad Khan, the Welsh jihadi killed in a drone strike, and commented on a newspaper article when Khan's mother appealed for her son to come home in 2014 before he was killed.

Hisham wrote: 'Inshallah we go together, man.'

Abedi's sister Jomana, 18, attended the school in Whalley Range that hit the headlines in 2015 when twin pupils, aspiring medical students Zahra and Salma Halane, left their homes and moved to IS-controlled Syria.

Armed police carrying assault rifles were quick to arrive at the scene at Manchester Arena last night

SAS TROOPS DRAFTED INTO MANCHESTER AS PM CONSIDERS PUTTING ARMED SOLDIERS ON STREETS SAS troops were drafted into Manchester yesterday to support the police as counter terror officers launched a major operation to find friends and relatives of the suicide bomber. The 20 strong heavily armed team were flown north as part of a contingency plan to counter any surge in extremist violence - such as a hostage situation - that will require military intervention. Under the direction of the Counter Terrorist Command the soldiers, many of who have worked with specialist police unit in the past few years, were on standby to join undercover teams and armed response units deployed in the city. The move came as Air Marshall Sir Stuart Peach, the head of the UK's armed forces, told a Cobra meeting that the military was ready to put armed soldiers on the streets if directed by the Prime Minister. As part of an ongoing high readiness response, codenamed Op Temperer, Army commanders have three infantry battalions of armed soldiers ready to deploy anywhere across the country to support the police. The Prime Minister is understood to be reviewing a wider intelligence assessment from officers at the Joint Terrorist Analysis Cell, before making any decision on the deployment of armed soldiers on mainland Britain. The rotation of available soldiers changes on a regular basis with paratroopers from 16 Air Assault Brigade currently listed as the 'in role' force ready to provide additional public security. Advertisement

Eight of the 22 victims have been named as college student Georgina Callander, eight-year-old schoolgirl Saffie Roussos, 26-year-old John Atkinson, Kelly Brewster, 32, and Megan Hurley.

Ms Brewster, an office worker from Sheffield, was said to have shielded her niece, Hollie, 11, when the bomb went off.

Alison Howe, 45, and Lisa Lees, 43, from Royton, in Oldham, were named among the dead tonight. They had been waiting in the foyer for their 15-year-old daughters Darcia Howe and India Lees.

Olivia Campbell, 15, who twice entered Britain's Got Talent, was confirmed dead by her mother Charlotte, 36, on Facebook.

She wrote: 'RIP my darling precious gorgeous girl...taken far far too soon, go sing with the angels and keep smiling mummy loves you so much.'

Saffie Rose Roussos, 8, is the youngest known victim of last night's atrocity. Her mother, Lisa, was criticially injured and neighbours say she does know her daughter had died

Kelly Brewster died as a result of her injuries, her family has confirmed. She had been missing since the atrocity last night

The first victim of the Manchester terror attack has been named locally as 18-year-old Georgina Callander. She is pictured with Ariana Grande two years ago

This image, believed to be of victim John Atkinson (pictured left), 26, from Bury, has been posted on Facebook by a friend

The headteacher of the school of the youngest victim named so far, Saffie Roussos, said she was 'simply a beautiful little girl in every aspect of the word'.

Tracey Radcliffe, a leader at 1st Tarleton Brownies, added: 'Saffie was an adorable and lovable little girl - she really was.

'I didn't know her parents, but she was just lovely. No one should go to a gig and not return.'

A close friend of victim Georgina Callander said she died in hospital with her mother at her bedside in hospital.

Another friend tweeted: 'A beautiful girl with the kindest heart & soul, I'll miss you forever, may you rest in a better place than here. I love you.'

Victim Mr Atkinson, from Radcliffe, was leaving the concert at the venue when it was targeted by the suicide bomber.

Friends and family have paid their respects online, describing him as an 'amazing young man'.

Lee Paul posted on Facebook: 'Sleep tight John Atkinson. Thoughts and prayers with all your family and the other 21 people who lost there lives last night.'

Tracey Crolla wrote: 'Thinking of all the Atkinsons at this very sad time John Atkinson you turned into an amazing young man so kind and thoughtful you will be missed by everyone x x.'

Megan died in last night's attack after watching singer Ariana Grande at the MEN Arena, while her brother Bradley was injured, a fundraising page has revealed.

Friends have posted heartfelt tributes to the youngster.

The page was set up by friend Helen McDermott to give Megan 'a beautiful send off' and has already raised more than £1,800.

Ms Brewster died as a result of injuries suffered when she 'shielded' her young niece from the deadly blast.

Officers confirmed to family members that she had died at 10.30pm last night.