'Mother of Satan' explosive

THE explosive used in the London bombs has been popular among Middle East extremist groups for many years and can be made from household items.

Known as acetone peroxide, TATP, or Mother of Satan (because of its instability), it was used by the British-born shoe-bomber Richard Reid in conjunction with a plastic explosive.

Thirteen men are currently on trial in Jordan for a plot to use acetone peroxide bombs in a chemical attack. They include Abu-Musab al-Zarqawi, al-Qaeda's top man in Iraq, who is being tried in absentia.

The explosive is thought to be favoured by al-Qaeda and in 1995 an accident involving its preparation led police in the Philippines to two of the men wanted in connection with the first attack on the World Trade Centre two years earlier.

One of the attractions of the explosive to terrorists is the difficulty of detecting it with normal airport security measures.

It is also possible to make it from household items, such as drain cleaner (sulphuric acid), hair bleach (hydrogen peroxide) and acetone (used in some nail varnish removers).

Dr Marina Murphy, of Chemistry and Industry magazine, said the necessary ingredients were easily accessible in quite large quantities to anyone working in a chemistry lab.

The major drawback with the explosive is its volatility.

Acetone peroxide is highly sensitive to heat, friction, and shock, and even a small jolt or a cigarette being lit nearby can set it off.

Professional chemists have been injured attempting to use it and dozens of Palestinian bombers have been killed handling it.