Police reportedly found IS propoganda videos on his cellphone, but after an investigation, they failed to find sufficient evidence of links to terrorism to prosecute him.
All three men involved in the attack were confronted and shot dead by armed officers within eight minutes of the first call. During the attack, seven people were killed and dozens more were wounded.
Corriere wrote that Zaghba was stopped at Bologna airport in 2016 when he was trying to fly to Syria via Turkey, and that Italian authorities had tipped off Britain about his movements. He was allegedly on his way to Syria and was carrying only a backpack.
"It is seeking to project its influence and maintain its relevance by inspiring, encouraging, and - though there does not appear to be evidence of this in the latest United Kingdom plots to date - directing attacks in Europe and elsewhere", he said.
Youssef Zaghba, 22, was the son of an Italian mother and a Moroccan father who had separated, and was registered as an Italian living overseas, said Daniele Ruscigno, mayor of Valsamoggia, near Bologna.
A London mosque said Butt "infrequently" attended prayers there but was asked to leave after an incident a few years ago where he interrupted a Friday sermon, according to a statement from Jabir bin Zayd Islamic Centre.
There has been no official comment on the reports from United Kingdom authorities, but Scotland Yard said Zaghba was not a police or MI5 "subject of interest". The 48 injured included people from France, Spain, Australia and New Zealand.
"The attack, the third in Britain in three months, has raised questions over the government's ability to protect Britain following cuts to police numbers in recent years".
Police in the United Kingdom investigating Saturday's terror attack in London have released the identity of the third terror suspect. Two people believed to have documents linked to Redouane were arrested in Ireland, though only one remained in custody Wednesday.
"A small number of the highest priority investigations involve current attack planning, and these investigations command a significant proportion of our resource", police said.
In his neighbourhood, Butt was known as Abu Zaitun - or Abu for short.
The UK Metropolitan police confirmed the media reports.
After the airport stop, Italy's Internal Intelligence Service passed on details to the liaison officer for the U.K.'s foreign security agency - MI6 - in Italy, who also relayed the information to MI5, two Italian security sources said.
The latest opinion poll on voting intentions, by Survation for ITV, had the Conservatives' lead over Labour narrowing to just one point from six points in the same poll a week earlier. May was Home Secretary prior to becoming prime minister previous year.
The security agencies are already facing criticism for supposed failures over the attacks in Manchester, Westminster and London Bridge. The assault was continued by the attackers in the adjacent Borough Market area which is a popular bar and restaurant district.
Transport for London, which oversees the capital's transport network, has advised commuters to make alternative journeys as the station will be busy. In what it said was an unprecedented move, the Muslim Council of Britain said more than 130 imams and other religious leaders had refused to perform the traditional Islamic funeral prayer for the attackers.
The threat level remains at moderate but frontline Gardaí have warned they've had no counter-terrorism training.
It had been set at "critical" in the days after the Manchester concert bombing on May 22 that killed 22 people - reflecting a judgment that an attack might be imminent because accomplices with similar bombs might be on the loose.
Macron hits out at Russian media, Putin denies hacking
Versailles was chosen for the Macron-Putin meeting because an exhibition dedicated to Tsar Peter the Great is opening there. The regime of Syrian president Bashar al-Assad has repeatedly used chemical weapons with impunity.
Muguruza marches on in Paris
Kazakh 27th seed Putintseva enjoyed her best Grand Slam performance in Paris past year when she made the quarter-finals. The 2017 French Open is shaking down to be quite interesting thus far, and on Friday the third round will get underway.
How Herrera became unlikely leader of Mourinho's United
Phil Jones admits that Manchester United's season hinges on beating Ajax in the Europa League final in Stockholm on Wednesday. We've had a few managers, different players coming and going, but I feel really happy to be at this club.
Meet Apple's Echo Rival, Homepod
It's created to respond in a natural, conversational manner to voice queries, and is also powered by cloud-based AI technology . Sources state that while the device will be shown off at WWDC, it won't actually ship to customers until later on in 2017.
London attacks: What we know
After ramming the auto into a barrier outside the Houses of Parliament, the driver got out and stabbed a police officer to death. European security official says it is too soon to say whether incidents around London Bridge are militant attacks.