These are the tests Thailand says prove a British-made bomb detector isn't doing its job properly.

The government has halted plans to buy any more of the GT200 detectors after its own experiments suggested the machines had only a 20 percent success rate in correctly spotting hidden explosives.

Thailand's prime minister announced the decision.

[Abhisit Vejjajiva, Thai Prime Minister]:

"Using this device in the test it was found that it could detect the exact explosive boxes only four out of 20 times. It shows it's

insignificant, that it is no different from a random process. Therefore it's obvious that we will not buy anymore of these devices."

The UK government has banned exports of a similar British-made detector, the ADE651, to Afghanistan and Iraq because of fears over their effectiveness.

Thailand has already got more than 530 of the GT200 machines which cost up to 36, 000 dollars each.

It's been widely used in security operations in southern troublespots where six years of unrest have claimed more than 3, 900 lives.