Third London Bridge attacker an Italian national

Youssef Zaghba was a 22-year-old Italian national of Moroccan descent (L)

The third of the three London Bridge attackers was on Tuesday named as Youssef Zaghba, a 22-year-old Italian national of Moroccan descent, who was on Italy's list of persons at risk after being held last year while on his way to Syria.

Zaghba had an Italian passport and his mother's name is Valeria, informed sources told Italian media Adnkronos, reports Efe.

Zaghba was shot dead by police along with two other accomplies after Saturday's deadly rampage in which seven people were killed and 48 were injured.

British police said on Tuesday they believed Zaghba to be the third attacker, that he was an Italian national of Moroccan descent and that his family had been informed.

"He was not a police or M15 subject of interest," the statement said.

At the time of the London Bridge attacks, Zaghba had been working in a London restaurant and was in touch with his mother.

There were conflicting reports on the mother's whereabouts, with some sources saying she was in Bologna in Italy and others claiming she was in Casablanca, Morocco.

Zaghba's parents reportedly lived in Morocco but then separated and his mother settled in Bologna. Zaghba spent a lot of time with relatives in East London but visited his mother several times in Bologna.

When Zaghba was stopped at the city's Marconi airport in March 2016, he had told his mother he was going to Rome.

At the time of his arrest, Zaghba was travelling with just a backpack and his passport was impounded. His mobile phone was also confiscated and was found to contain religious videos and images but no violent 'jihadist' images.

He was, however, charged with international terrorism and recorded on intelligence files as a suspected foreign fighter.

Although the charge was later withdrawn, he remained on file as "a person at risk", Italian daily Corriere della Sera reported.

Italy's intelligence services had reported Zaghba and his frequent movements to Moroccan and British authorities, Corriere reported.

Zaghba's fellow attackers were named as Pakistan-born British citizen Khuram Butt, 27, and Rachid Redouane, 30, a Moroccan-Libyan pastry chef who had an Irish wife.

All 12 people arrested on Sunday after the attack have now been released without charge while a 27-year-old man was held in Barking near London on Tuesday in connection with the investigation, police said.

Daesh claimed Saturday's attack in which Zaghba, Butt and Redouane drove a hired van into pedestrians on London Bridge at around 10 pm before stabbing people in the area around the nearby Borough Market.

Zaghba, Butt and Redouane were all shot dead by police at the scene within eight minutes of receiving an emergency call.