Police believe the bomber entered the arena through a subway station, detonating the bomb near the ticket area just as people were leaving the concert.
British Prime Minister Theresa May chaired a meeting Wednesday of her emergency security cabinet group to talk about intelligence reports on Abedi and concerns that he might have had outside support.
Up to 5000 soldiers and special forces personnel, alongside armed police officers, will also deploy on to key streets across the United Kingdom and around expected targets, under a previously revealed plan called "Operation Temperer".
May revealed that continuing investigations after the suicide bombing in Manchester Arena by Salman Abedi revealed the possibility that there is a wider group of individuals behind the attack that killed 22 people and injured almost 60.
The US intelligence official, who has direct knowledge of the investigation, said Abedi, whose family is of Libyan descent, was identified by a bank card found in his pocket at the scene of the explosion.
Police have said that a 23-year-old man has been arrested in relation to the bombing, but it is unclear whether the man was arrested during this raid or at another location.More news: North Korea: New missile an 'answer' to Trump's policies
Over 20 people were killed during the Manchester terror attack.
The PM said the threat level "should be increased, for the time being, from severe to critical".
Islamic State claimed responsibility for what it called a revenge attack against "Crusaders", but there appeared to be contradictions in its account of the operation. British officials, however, have not commented on whether Abedi had links to IS or other extremist groups. "They are there to help our police service to keep us safe and guard key sites", he said. Officials said 59 victims were hospitalized - some reportedly paralyzed by shrapnel.
Collomb, who spoke with May after the attack, said the two countries should continue cooperating closely on counterterrorism efforts despite Britain's pending exit from the European Union.More news: Michael Flynn's Businesses To Be Subpoenaed
Saffie's mother, Lisa Roussos, and her sister, Ashlee Bromwich, survived and were being treated for their wounds in separate hospitals.
Charlotte Campbell said, "She's my baby".
Asked whether the U.S. leaks had compromised the investigation, she said: "I wouldn't go that far but I can say that they are perfectly clear about the situation and that it shouldn't happen again".
"Saffie was simply a lovely little girl in every aspect of the word", said Chris Upton, the head teacher at Saffie's school.
Katz reported from London.More news: Rouhani declared victor of Iran's presidential vote, state TV
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