EXPLOSIVES found by detectives investigating the London bombings were home-made using ingredients that can be found in high street chemists.
The highly volatile explosive - acetone peroxide - has been discovered in a house in Leeds thought to have been used as a bomb-making factory.
The discovery has raised fears of other British fanatics making their own explosives and following the example of the London suicide bombers.
Instructions for making acetone peroxide are readily available on the internet.
The home-made explosives found in Leeds are similar to those used in other al-Qaida-linked attacks. They were also used by shoe-bomber Richard Reid.
Police are hunting an Egyptian chemistry student who has fled his Leeds home as well as the suspected mastermind behind the suicide attacks.
A security source said: "The explosive that has been recovered at the house in Leeds - some of it is still in there - is in fact acetone peroxide.
"It's the same kind of explosive Richard Reid had in his shoes when he tried to blow up a trans-Atlantic flight in 2001.
"This is a shocking development in the sense that earlier ideas about commercial or military grade explosive being used in the bombs themselves would therefore seem to be wrong."
He said the explosive's "extremely volatile" nature had prompted the police to widen a cordon around the house in the Beeston area of Leeds even further yesterday, as well as set up a no-fly zone.
Anti-terrorist agencies are worried other "educated amateurs" could try to make more of the explosive.
Metropolitan Police Commissioner Sir Ian Blair said today that he expected the investigation into the London bombs to uncover a "clear al-Qaida link".
Sir Ian issued a fresh warning there was a "very strong possibility" of further terrorist attacks following the blasts last week which left at least 54 dead.
He said that the police effort was now concentrating on finding the handlers and bomb-makers who organised the attacks by the four suicide bombers.
Detectives were today hoping that chilling CCTV pictures of a teenage suicide bomber will help bring forward new information today about the London terror attacks.
The grainy images show Hasib Hussain, 18, carrying his bomb in a military-style rucksack through Luton railway station on his way to the capital last Thursday.
Police confirmed the number known to have been killed in the attacks last night rose to 54, after a man died in hospital.
He had been a passenger on the number 30 bus when Hussain detonated a ten-pound load of high explosive as it pulled into Tavistock Square.
The teenage bomber killed at least 13 innocent victims in his suicide mission, two and a half hours after he was filmed in Luton at 7.20am.
Dressed casually in a dark anorak-style jacket and dark trousers, he looked like thousands of other young tourists heading for the capital.
Hussain, who had travelled to Luton by car from his home in West Yorkshire that morning, boarded a Thameslink train to King's Cross with his three fellow suicide bombers.
The other three then simultaneously detonated their devices on London Underground trains at 8.50am, but Hussain did not blow himself up on the bus until 9.47am.
Detectives released the CCTV footage of him at Luton as part of a public appeal.
MUSLIMS CANCEL PLAN TO STAGE ANTI-TERROR MARCH IN CAPITAL
A PLANNED march by Muslims in Edinburgh to demonstrate their opposition to the London terrorist attacks has been cancelled.
Muslim leaders met to discuss a possible march at the weekend, but have decided to hold low-profile local events instead.
Smaller-scale prayer meetings and vigils are now set to be held across Scotland to help remember those who lost their lives in last week's attacks.
Jalal Chaudry, chair of the Islamic Society of Scotland and a member of the Muslim Council of Britain, said: "It was felt there was not enough notice for people to travel from all over Scotland to a march."