Yousef Zaghba was placed an international “watchlist” of suspected jihadis after the Italian police caught him trying to travel to Syria last year.
Italian officials claim both MI5 and MI6 were warned about Zaghba’s jihadi aspirations after he told police he was "going to be a terrorist" when he was stopped at Bologna airport, according to the Telegraph.
Italian counter-terrorist agencies have played down the extent to which they shared information with British security chiefs about Youssef Zaghba.
The 22-year-old Italian national was still allowed to enter Britian, where he went on to join Khuram Butt and Rachid Redouane in killing seven people on London Bridge last Saturday night.
Police have named Yousef Zaghba as one of the London terror suspects
Boris Johnson has questioned “how on earth" the security services failed to allow Butt "through the net" after he appeared on a Channel 4 documentary entitled "The Jihadis Next Door”.
The 27-year-old is said to have been deemed low-risk by authorities despite being reported twice to counterterrorism agencies after he was apparently brainwashed by watching extremist YouTube videos.
The third London attacker, Rachid Redouane, was reportedly refused asylum in Britain in 2009 yet appeared to have been able to stay on in the country.
Morning after London attack: Heightened police presence at Borough Market & Bridge Sun, June 4, 2017
SIX people have been killed after a horrific terror attack targeted London Bridge and Borough Market on Saturday night. These are the pictures are London wakes up to the tragic scenes
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One of the three attackers is said to have been carrying an identity card issued in Ireland when he was shot, according to Dublin security sources.
Seven people were killed on Saturday night after the three terrorists drove a van through pedestrians on London Bridge before jumping out of the vehicle and launching a knife attack on revellers in Borough Market.
At least 48 people were injured, many with life-threatening conditions, before armed police shot and killed the three suspects within eight minutes of the first call to emergency services of the incident.
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The London Bridge attackers
Forensic investigators at London Bridge
We should make it easier for the authorities to deport foreign terror suspects
Theresa May said ”enough was enough" with Islamist extremists and has now threatened to rip up human rights laws to ensure that terrorism suspects can be deported or have their freedom curbed.
Mrs May told a rally of Tory supporters in Slough, Berkshire: “We should make it easier for the authorities to deport foreign terror suspects to their own countries.
“We should do even more to restrict the freedom and the movements of terrorist suspects when we have enough evidence to know they present a threat, but not enough evidence to prosecute them in full in court. If human rights laws get in the way of doing these things, we will change those laws to make sure we can do them.”
Sadiq Khan leads sombre vigil for London terror victims Tue, June 6, 2017
London Mayor Sadiq Khan lead a vigil to commemorate the victims of the London Bridge terror attack. Hundreds attended the event outside London's City Hall
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London Mayor Sadiq Khan bows his head
Her comments come after Home Secretary Amber Rudd revealed the Government had finally begun using its powers to ban ISIS jihadis from returning to Britain – which has originally been introduced by David Cameron two years ago.
Ms Rudd would not reveal how many Temporary Exclusion Orders had been issued but added the number is "is no longer zero" following the Manchester bombing just weeks ago.