The bomb that exploded outside the Women's Hospital contained ball bearings that would have acted as shrapnel and could have caused "significant injury or death".
Counter terror police are still probing how and why it was detonated but believe it could have been ignited by the taxi carrying Emad Al Swealmeen coming to a stop.
Investigators have established the 32-year-old's Improvised Explosive Device was homemade, with the ingredients bought over many months and under a host of different names.
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As work continues to understand Al Swealmeen's motives and intentions when he took his bomb into the taxi driven by David Perry on Sunday morning, Counter Terror Police North West released more details about their findings so far.
The unit's Assistant Chief Constable Russ Jackson said: "Although there is much scientific work to do on the device to determine what made it up, we have learned a great deal over the past five days.
"It was made using homemade explosive and had ball bearings attached to it which would have acted as shrapnel.
"Had it detonated in different circumstances we believe it would have caused significant injury or death.
"We still do not know how or why the device exploded when it did, but we are not discounting it being completely unintentional, and it is a possibility that the movement of the vehicle or its stopping caused the ignition."
Al Swealmeen is believed to have been plotting for at least seven months, with detectives having traced the purchase of bomb making material to April 2021 - around the time he began renting a flat on Rutland Avenue, near Sefton Park.
"Significant items" have been recovered there and at the Sutcliffe Street address in Kensington he has also been linked to.
Al Swealmeen, who was from Iraq, is known to have operated under a number of aliases, including Enzo Almeni.
Other fake identities are also being examined, ACC Jackson confirmed.
He said: "We are spending considerable time seeking to understand the way the purchases for the ingredients to make the device were made.
"This is complicated because purchases have spanned many months and Al Swealmeen has used many aliases.
"We are confident however that in time we will get a full picture of what purchases were made and how, and if anyone else was involved or knew what Al Swealmeen was up to.
"We have found no connection between this incident and the terrible events of Manchester in May 2017.
"The device was also different to the one used in the Manchester Arena attack."
In a further development, police have now spoken to the brother of Al Swealmeen as well as others who knew him.
ACC Jackson added: "Officers spoke with the brother of Al Swealmeen yesterday evening and this has given us an insight into his early years and an understanding of Al Swealmeen's life and his recent state of mind which is an important line of investigation.
"We are grateful for members of the public who knew him and have contacted us."
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