The BBC is airing a fascinating radio documentary on Semtex, one of the world’s most lethal explosives.

Extremely powerful and easily concealed, Semtex is a favorite weapon of terrorists. It was Semtex that exploded on Pan Am Flight 103 in December 1988, killing 259 people on board and 11 residents of  Lockerbie, Scotland.

Semtex takes its name from the town of Semtin in the Czech Republic where it is still produced today.

Tons of it were shipped — at Moscow’s approval — to the North Vietnamese Army. When the Vietnam War ended, a new customer was found: Libya.

No more than 11 ounces of the yellowish explosive brought down Pan Am 103, yet Czech President Vaclav Havel revealed that 1,000 tons of it was shipped to Libya — a claim the company disputes.

Libya, in turn, supplied Semtex to terrorist groups like Black September and the IRA. The IRA began receiving significant quantities of Semtex after the 1984 murder of a policewoman in London led to a breakdown in UK-Libya relations.

The “Semtex families” are a group of 147 British families who lost relatives and loved ones in the 1970s and 1980s to IRA bombs packed with the plastic explosive. They are now seeking $1 billion in compensation from Qadaffi’s regime.

The BBC finds the Explosia company that produces Semtex and is very touchy about what it calls the “hysteria” that surrounds Semtex. (Read Explosia’s 10 myths about Semtex.)

Listen to the documentary here.