Two of the three London Bridge terrorists have been named by Scotland Yard as Khuram Shazad Butt and Rachid Redouane.
Butt, 27, a British citizen who was born in Pakistan, is thought to have featured in a controversial Channel 4 documentary last year.
He was known to the police and MI5, Assistant Commissioner Mark Rowley confirmed, but there was no intelligence to suggest that this attack was being planned, it added.
Redouane, 30, had claimed to be Moroccan and Libyan. Sky News is reporting an Irish ID card was found on Redouane, who was not known to police.
Both are from Barking. The third attacker has yet to be named.
In footage that could raise difficult questions for the security services, Butt is shown in a programme called The Jihadis Next Door, where he is seen with an Islamic State flag in Regent’s park trying to radicalise children.
The Channel 4 programme shows Butt, initially named as Abz, at an event with Mohammed Shamsuddin - thought to be the ‘new Jihadi John’ - who speaks of the “real possibility” that the Islamic State flag will one day fly over Downing Street.
The footage was shot by the broadcaster in January 2014, nine months before Dhar was arrested by counter-terrorism police. He later skipped bail and was thought to have travelled abroad to Syria with his wife and four children.
The trio, wearing fake suicide bomb vests, were shot dead by eight officers outside a pub after police opened fire with an “unprecedented” hail of 50 bullets. One was carrying an identity card issued in Ireland when he was shot dead, security sources in Dublin said.
Seven people were killed in the attacks in London on Saturday night and 48 people are in hospital, with 21 fighting for their lives.
Pedestrians were mowed down by a van on London Bridge before attackers stabbed a police officer and revellers around Borough Market. One of the attackers shouted “this is for Allah” as he knifed a man near a pub - while the Islamic State militant group claimed its fighters carried out the attack.
Officers arrested a dozen people in raids on flats in Barking, east London, on Monday morning where residents said they believed one of the terrorists may have lived.
The Sun quoted a friend of Butt - again using his Abz moniker - as saying he called police about the 27-year-old’s extremist views which were said to have been ignited by YouTube videos.
The source, who has not been named, said he contacted police in Barking, east London, after the Watford-born married father-of-two discussed Islamic State-inspired terror attacks. One of Butt’s children was three, the other just months old.
After confirming Butt was allowed to keep his passport and was not arrested, he added: “I did my bit, I know a lot of other people did their bit, but the authorities did not do their bit.”
The BBC stressed in a report on the Today Programme on Monday that the claim could not be verified and needed to be considered in the context of the 22,000 calls the anti-terrorism hotline received last year alone.
Meanwhile, the family of Butt have reportedly asked to be left alone to “grieve in peace”. The Sun quoted the killer’s brother-in-law as saying his family did not know what was going on and requesting space to mourn.
The newspaper said Butt was the terrorist pictured lying dead in an Arsenal shirt outside the Wheatsheaf pub, after being killed by police. He was said to have been born in Pakistan but was brought up in the UK.
It further claimed that Butt was a former Transport for London, Topshop and KFC worker and had appeared in Channel 4 documentary The Jihadis Next Door, where he was seen trying to radicalise children in his local park.
A friend told The Sun: “Back then he had a reputation for being a bit shady and taking drugs.”
The source added: “But all that changed when he became radicalised.
“He began stopping his neighbours in the street and asking them if they had been saying their prayers and when they had been to the mosque.”
Erica Gasparri was further quoted in the Daily Record as saying she had also raised concerns about Butt. She said he used to sit in a park opposite Northbury Primary School in Barking with two other men and talk to local children.
The mum-of-three said Butt would offer the kids sweets and claim to be “teaching them about religion”.
Another local who knew the attacker said he was kicked out of a mosque last year for supporting IS. MailOnline reported that Butt was thrown out of the Jabir Bin Zayd mosque in Barking after interrupting a sermon to say that voting in the general election was “un-Islamic”.
The manager of the mosque, who did not want to give his name, told the website that Abz halted the iman who was advising the community to vote. “He started saying that voting was un-Islamic and we shouldn’t do it,” the manager said.