The briefcase bomb used in the July 20 plot used a captured British pencil detonator inserted into a block of British plastic explosives weighing approximately two pounds.

Since going on the run a week ago, I'd carried with me a briefcase bomb - small explosive charge, but mostly jellied gasoline - for just that purpose.

However, the meet ends in disaster when Walker remotely detonates a briefcase bomb carried by a double, killing al-Zahrani and three bystanders.

"If you're talking about a briefcase bomb or nerve gas that someone is going to toss into the reflecting pool," he said, "you have a situation where you're putting people in harm's way."

Staff officer Colonel Claus von Stauffenberg would carry a briefcase bomb into a daily conference meeting and place it just a few feet away from Hitler.

He was stopped by security guards at the entrance, after which he opened fire and detonated a briefcase bomb, killing himself and two guards, witnesses said.

Stauffenberg's briefcase bomb failed to kill Hitler on 20 July 1944, and Ewald von Kleist-Schmenzin was arrested the next day.

On 20 July 1944 he was standing at the end of the conference table close to von Stauffenberg's briefcase bomb.

One document described the use of briefcase bombs by Iraqi terrorists.

Al-Qaeda claims to have purchased "smart briefcase bombs" with nuclear capabilities on the black market.