The London bombers left a stash of 16 unexploded bombs in a car, some packed with nails.
Security experts believe the July 7 plot, which killed 56 people, may have been much larger and the explosives intended for a second strike.
The bombs (pictured) were recovered from a car believed to have been rented by suicide bomber Shehzad Tanweer, according to ABC News.
A picture of one of the bombs (left) shows nails bulging out of the side of a bottle-shaped bomb and (right) some of the bombs flat-packed like pancakes
The vehicle was found five days after the attacks in Luton, where the bombers boarded a train to London.
Exclusive pictures obtained by the US network show some of the bombs flat-packed like pancakes, while others were packed with nails to use as shrapnel. An X-ray picture of one of the bombs shows nails bulging out of the side of a bottle-shaped bomb.
Security analyst Robert Ayers, said: "Bombs don't kill by concussion. Small bombs, they kill by the blast effects of fragments of glass or metal, and this is designed to kill people."
He said he believed the explosives were left for a second strike.
Meanwhile, police released new details about the movements of the suspected Shepherd's Bush bomber last night.
The first image of the suspect released last week showed him at Westbourne Park Tube in a short-sleeved, dark blue England football shirt.
Mr Clarke said police now believed that he threw away the shirt after fleeing the scene. He said it may have been turned inside out and stained with mud. It was probably left in McFarlane Road, near Wood Lane, he added. The suspect was later seen wearing a white vest. The new image of him released last night showed him on a Number 22 bus.
Peter Clarke, head of the Met's Anti-Terrorist Branch, said: "We think he got on the bus in Wood Lane at about 1.20pm and stayed on until the end of the route at Mapleton Rd, Wandsworth.
"This is near the junction of Garratt Lane, close to the Arndale Centre. He got off the bus at 2.07pm."
The picture was released as police raided a flat in south London.
A spokesman said officers had entered premises at Blair House in Stockwell. south London as part of "our ongoing investigation into the incidents of Thursday".
He said armed officers were present as a precaution. Local resident Samiullah Ainullah, who lives in Blair House said he had been sleeping when the police arrived.
He said they took four women out of the house who were with a boy aged eight or nine and two other smaller children.
"They were young women. The police took the children away and then handcuffed the women. Then they drove all of them away."
Sonia Abreeu, who lives at No 42, said her husband had gone for a jog shortly before 6pm, but then returned immediately and said the police were there and were telling everyone to go outside.
"They asked everybody to go out, they were shouting don't go that way, and took us away from No 40."