CONTROVERSY over the UK's counter-terror efforts spread to border security after claims emerged that another of the perpetrators was let into the country despite being on a security watch list.
Youssef Zaghba is said to have been stopped by Italian officers trying to travel to Syria last year.
Prosecutors in Italy say there was not enough evidence to arrest or charge the 22-year-old when he was intercepted at Bologna airport.
However, unconfirmed reports suggest he was placed on the Schengen Information System (SIS II), a vast database of alerts about individuals and objects of interest to EU law enforcement agencies.
It contains information on thousands of people wanted under the European Arrest Warrant, as well as suspected foreign fighters.
Alerts are made available in the UK through the police national computer and to Border Force officers at immigration controls.
Authorities are facing pressure to detail whether an alert was flagged about Zaghba when he came into the UK and whether he was stopped at the border.
The Home Office has not commented as there is an ongoing police investigation, while Scotland Yard has said Zaghba, who lived in east London, was not a police or MI5 subject of interest.
Questions over the extent to which the terror gang were known to security services have been mounting since it was revealed Butt had been investigated in 2015.
The revelation meant perpetrators in all three of the terrorist outrages to hit the UK this year had been on the radar at some point.
Zaghba, Pakistan-born British citizen Khuram Butt and Rachid Redouane (30), who claimed to be Moroccan-Libyan, launched a rampage around London Bridge and Borough Market on Saturday night.
The rampage was brought to an end when the trio were shot dead by armed police eight minutes after the first emergency call.
