Latest: Britain was braced for further terrorist attacks following the Manchester atrocity as Theresa May said the threat level was being raised to its highest possible rating.
Update 9.50pm: Britain was braced for further terrorist attacks following the Manchester atrocity as Theresa May said the threat level was being raised to its highest possible rating.
In a live televised statement from Downing Street, the UK Prime Minister said the terror threat level would be increased to "critical", meaning an attack was expected imminently as it was possible a "wider group of individuals" could have been involved in the Manchester Arena attack rather than just suicide bomber Salman Abedi.
In a sign of the increased threat, the military could be deployed to support armed police officers, Mrs May said.
Monday night's attack at a concert by US pop star Ariana Grande left 22 people dead, including an eight-year-old girl, and dozens injured.
Speaking at Number 10, Mrs May said: "The spirit of Manchester and the spirit of Britain is far mightier than the sick plots of depraved terrorists.
"That is why the terrorists will never win and we will prevail."
Mrs May will chair a meeting of the Government's emergency Cobra committee at 9.30am on Wednesday, Downing Street has announced.
Update 8.32pm: The author of a poem which stirred the emotions of mourners at a vigil in Manchester has said it was a "privilege" to read it.
Poet Tony Walsh, 51, delivered a version of his poem This Is The Place, an ode to the city of Manchester and its people, to a packed Albert Square.
He told the Press Association: "As a proud Mancunian, I was worried that I'd find that emotional, particularly when I mentioned my mum, who passed away a while ago.
"It meant a lot to me. I wanted to do it for Manchester. I didn't want to crack, because Manchester won't crack.
"I felt quite calm actually, when it came to do it.
"It was a privilege."
The poet, originally from Tameside, said the poem was previously commissioned by a charity called Forever Manchester.
"There was flashes of humour in there because that's Manchester all the time, and it's Manchester even in its darkest hours.
"And it's important to me that the poem is true to Manchester and its people, and we fight through these things with humour, as hard as it is sometimes. That's the Mancunian way," he said.
Mr Walsh, who now lives in Prestwich, said he is often commissioned to write about the city.
He has also previously written a poem to commemorate the 20th anniversary of the Manchester Arena two years ago.
Update 7.41pm: A candle-lit vigil in Birmingham in memory of those killed in the Manchester Arena bomb attack was cut short after a man believed to be armed was detained nearby.
The man shouted out as he was handcuffed and led away by officers with West Midlands Police, just a short distance from where 1,000 people had gathered in the city's main Victoria Square.
As he was taken away in a riot van in Edmund Street, which runs behind Birmingham's council house, a police sergeant could be seen carrying away what appeared to be a bat and a hatchet.
Speakers who had been paying tribute to the Manchester victims were interrupted by the man's loud protests, from down a side street.
Police, including armed response officers, then cleared the square a short time later.
The force's chief constable David Thompson - who had been attending the vigil in an official capacity - witnessed some of the incident.
He confirmed the evacuation of the square, in front of the council house, had been a precaution.
Update 7.25pm: Scottish teenager Laura MacIntyre, who was reported missing after the Manchester terror attack, is being treated in hospital for serious injuries, family friend and SNP candidate Angus MacNeil has said.
Earlier:Thousands of people have gathered in the centre of Manchester in a show of defiance, declaring they will not be "beaten" or "intimidated" in the wake of the terror attack.
Crowds spilled from Albert Square on to nearby roads, standing together in an act of solidarity.
Lu Bowen, 40, brought flowers to lay as a mark of respect, and said it has been a "horrific" day.
Standing alongside her teenage daughter Lucy, she said: "We watched it all unfold last night.
"We felt we wanted to show a sense of solidarity and commitment that Manchester always has.
"When the chips are down, Manchester always pulls together."
She said some of her friends felt nervous about the prospect of coming into the city on Tuesday night, adding: "I personally just want to make a stand that even if my friends felt a bit nervous, I felt it was very important to prove that I won't be beaten, intimidated.
"And also, people have lost loved ones. If it was me, I'd want to see this."
Lucy said she had friends at the concert who were "shaken up", adding: "A few of them didn't come into school."
Her mother said: "It's been a horrific day. But we all feel the same here. We're here together."
Salman Abedi, the 22-year-old named as the suicide bomber behind Monday's terror attack on Manchester Arena, was born in the city and is believed to be of Libyan descent.
Abedi was registered as living at Elsmore Road in the city as recently as last year - where police raided a downstairs red-bricked semi-detached property on Tuesday as they hunted those thought to be behind the blast.
Neighbours recalled an abrasive, tall, skinny young man who was little known in the neighbourhood, and often seen in traditional Islamic clothing.
It was unclear whether he lived alone at the address, where a flag - possibly Palestinian - was occasionally seen flying from an upstairs window.
Neighbours said the young man had many visitors, one man dropping by regularly to pick him up in a Toyota Yaris.
Abedi is thought to have been of Libyan origin and born in Manchester.
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