A Newsnight investigation has discovered that a so-called "bomb detector" produced by a British company and sold for use in Iraq cannot work.

Following our revelations the government has announced a ban on their export to Iraq and Afghanistan. The Iraqi government has spent $85m on the devices, which are widely used.

There are concerns that the detectors have failed to stop bomb attacks that have killed hundreds of people.

Caroline Hawley reports.

Broadcast on Friday 22 January 2010.