Questions are also being asked about how much police and the intelligence services knew about the three men who carried out the attack on London Bridge and Borough Market before they carried out the deadly assault.

In the wake of Saturday’s attack, which killed seven people and left 21 in a critical condition, reports have emerged that one of the suspects was reported to police and may have previously been confronted by officers.

A woman named Erica Gasparri claimed she had reported her concerns about the individual in question’s extremist religious views to police two years ago after she feared he was radicalising children in a local park.

A former friend of the same man, whom neighbours have described as a married father of two young children who regularly attended two local mosques, also said he had contacted police in Barking, east London, about his views after he discussed Isis-inspired terror

He told BBC’s Asian Network his friend used to watch clips of the American hate preacher Ahmad Musa Jibril.

“I phoned the anti-terror hotline,” the unnamed man said. “I spoke to the gentleman. I told him about our conversation and why I think he was radicalised.”

Despite his warning he said his friend was not arrested and allowed to keep his passport. He said: “I did my bit, I know a lot of other people did their bit but the authorities did not do their bit.”

The same attacker was also reported to have appeared in a documentary on Channel 4 last year about British jihadis. He was caught on camera being involved in an altercation with police after an Isis flag was unfurled in Regent’s Park in London, according to the Mail.

It also said he was filmed alongside two notorious preachers who were well known to police and intelligence officials because of their extremist views.

Additionally, notes the Mail said were carried by a detective leaving a flat raided on Sunday in connection with Saturday’s attack suggested one of the individuals who is a subject of the investigation was questioned by officers.

The note captured on camera said: “He had been interrogated last year for his Islamic views, his house was searched, passport was taken + he had to sign on.”

It is not clear whether the notes referred to one of the three men involved in Saturday’s attacks or one of the individuals believed to be linked to them who were arrested on Sunday.

Salman Abedi, who murdered 23 people at an Ariana Grande concert at the Manchester Arena last month and Khalid Masood, who carried out the attack on Westminster Bridgein March that left five dead, using a similar modus operandi to Saturday’s attack, were both known to the security service but not part of any active investigation or regarded as a high risk and viewed as peripheral figures.

Cressida Dick, the Metropolitan police commissioner, said on BBC Radio 4’s Today programme that she could not comment on whether any of the three attackers were previously known to authorities, but said it was inevitable some such events would happen.

“I know people will be very concerned there have been three horrendous attacks in the past nine weeks. It’s worth pointing out also that we have foiled five attacks, and since 2013 we’ve foiled 18 attacks,” she said.

“Inevitably, [even] with a large database and some very good knowledge, on occasion somebody will, as my predecessor predicted, get through and be successful, and on occasion those people may have been known to the agencies before.”

GUARDIAN