One of the London Bridge attackers was able to enter the UK, despite being placed on an EU-wide watch list.

Youssef Zaghba, a 22-year-old Moroccan-Italian man who lived in east London, was named as the third attacker.

Zaghba was stopped at an Italian airport on his way to Syria last year and was put on an EU-wide database but was not prosecuted, according to reports. The Home Office has so far declined to comment.

Pakistan-born Khuram Butt, 27, and Rachid Redouane, 30, both from Barking were the other two attackers who killed seven people and injured 48 others on Saturday night.

Zaghba, Butt and Redouane drove a hired van into pedestrians on London Bridge at 21:58 BST before stabbing people in the area around Borough Market.

An Italian police source has confirmed  that Zaghba had been placed on a watch list, which is shared with many countries including the UK. In March 2016, Italian officers stopped Zaghba at Bologna airport and found IS-related materials on his mobile phone. He was then stopped from continuing his journey to Istanbul.

He was not prosecuted but was listed on the Schengen Information System, an EU-wide database which includes details of potential suspects.

When Zaghba entered Britain, staff at passport control should automatically have been alerted by the Schengen system.

“One unconfirmed report suggests that did happen, apparently when Zaghba arrived at Stansted Airport in January – but that border staff still let him in,” he said. On Wednesday, the Metropolitan Police said a 30-year-old man was arrested on suspicion of terror offences in Ilford, east London.

On Tuesday a 27-year-old man was arrested in Barking on Tuesday in connection with the investigation.

Scotland Yard have been criticised for the way they handled intelligence about Butt, who had been investigated by police and MI5 and featured in a Channel four documentary on extremism. Police said Butt had been subject to an investigation in 2015, but there had been no suggestion this attack was being planned.

Redouane was a chef who also used the name Rachid Elkhdar and police said he claimed to be Moroccan-Libyan. He married a British woman in Dublin in 2012 and lived in the city’s Rathmines area.

A man was arrested in Limerick, in the Irish Republic on Tuesday over the discovery of ID documents in Redouane’s name. He was later released without charge. A second man, who is in his 30s, was arrested on Tuesday evening, with the Garda saying it was also related to Redouane. He is being held in Wexford.