British authorities feel it's unlikely the Manchester suicide bomber built the bomb by himself.

He's been identified as 22-year-old Salman Abedi who was known to authorities.

ITV correspondent in Manchester Rupert Evelyn told Mike Hosking there's a genuine fear among the counter terrorism officers, that in order for him to achieve what he did, he must have had support.

"Of course we are left with a situation where ISIS have claimed so sort of responsibility for this attack. I think in time, we'll be able establish to whether or not that is true."

LISTEN ABOVE AS ITV CORRESPONDENT RUPERT EVELYN SPOKE TO MIKE HOSKING

Police swooped on the home of Abedi, blowing the door off his red-brick, semi-detached home in the Manchester suburb of Fallowfield on Tuesday in a controlled explosion designed to give them safe access to the property.

Inside, police found a disturbing clue. Forensic officers were pictured carrying out a copy of a booklet entitled "Know Your Chemicals".

Police said Abedi created a homemade bomb, that was deliberately detonated as concertgoers were leaving Manchester Arena after Grande's performance in order to inflict maximum damage.

Additional reporting news.com.au