The 22-year-old Italian national, who was of Moroccan descent, came from East London where some of the Metropolitan police’s investigation has been focussed.
His name is the last to be released after the other two attackers were named as Khuram Butt, a 27-year old Pakistan-born British citizen, and Rachid Redouane, a Moroccan-Libyan pastry chef aged 30.
Scotland Yard released a statement which said: "The Met’s counter-terrorism command has released the name and photograph of the third attacker shot dead by police following the terrorist attacks on London Bridge and at Borough Market on Saturday.
"While formal identification is yet to take place, detectives believe he is 22-year-old Youssef Zaghba, from east London.
His name is the last to be released after the other two attackers were named
All three men involved in the attack were confronted and shot dead
"The deceased's family have been informed.
"He is believed to be an Italian national of Moroccan dissent. He was not a police or MI5 subject of interest.
"All three men involved in the attack were confronted and shot dead by armed officers within eight minutes of the first call."
The trio ploughed into crowds before going on a stabbing frenzy
The trio ploughed into crowds before going on a stabbing frenzy around London Bridge and Borough Market, leaving seven people dead and dozens injured.
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According to Italian media the killer was stopped at Bologna airport in March last year while trying to board a plane to Istanbul before potentially travelling to Syria.
After telling his mother he was headed to Rome, he was stopped by authorities carrying just a backpack and a one-way ticket.
Zaghba’s was said to have been born to an Italian mother and Moroccan father, and they lived in Morocco before his parents separated.
London Bridge terror: Scenes as armed police respond Sun, June 4, 2017
At least two people have died after being after reportedly being struck by a van on London Bridge on Saturday night.
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Armed police responding to the incident at London Bridge
He is then believed to have lived in Bologna with his mother.
Police confirmed he was not a person of interest to the police or known to intelligence agency MI5.
Officers shot dead the attackers within eight minutes of receiving the first call on Saturday night after they plunged 12-inch knives into innocent bystanders.
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Armed officers took them down in hailstorm of bullets, firing an unprecedented 50 rounds at the men, who were wearing fake suicide vests.
As the terror probe continues another man 27-year-old man was arrested in Barking on Tuesday.
In total 13 people have been arrested, and 12 have been released without charge.
More to follow . . .