NINE other bombs were found in the back of teenage bomber Germaine Lindsay's car.
Police confirmed the red Fiat Punto found dumped at Luton train station was crammed with explosives.
Bomb disposal experts carried out a number of controlled explosions on the home-made devices last Tuesday.
Lindsay - who changed his name to Jamal after converting to Islam - is thought to have been carrying 10lb of high explosives in his rucksack which he detonated on the tube train from King's Cross to Russell Square.
At least 26 people died in the deadliest of the four July 7 attacks on the capital.
There are also claims Lindsay spent £900 on perfumes in the days before his deadly mission.
Experts believe they were used to fuel the deadly effects of the bombs - acting like napalm in the confines of a Tube train.
The bomber shopped near his home in Aylesbury, Buckinghamshire.
Intelligence sources have linked Lindsay, 19, who was raised in Rawthorpe, with the West Yorkshire cell's bomb factory, in Beeston.
The cell and their chemist - who police are still hunting - are believed to have used the terraced house to make and store the bombs.
The revelations came as an argument erupted between British and American intelligence agencies.
The FBI claimed they warned MI5 about Lindsay and even placed him under surveillance when he visited the States four years ago.
Whitehall officials denied knowledge of any link.
An MI5 source also confirmed they would review all terrorist intelligence gathered for the last five years in an attempt to find links.
American officials have also linked Lindsay with a plot to bomb a Soho night club with a truck packed with explosives.
British intelligence said they believed the Americans had confused Lindsay with another suspect with a similar name.