Dr Ian Oliver, an independent consultant for the UN International Drug Control Programme, has said every politician and public servant should be forced to sign a contract pledging to remain drug free. They would then submit to random tests and anybody found to be taking illegal substances would be offered counselling. Those who continued to take drugs would be disciplined.

Oliver, the former chief constable in Scotland, calls for the tests in his new book, Drug Affliction.

He has accused the government of sending out mixed messages. "Our [the British] government's policy is hypocritical ... if it was truly serious about drugs it would be saying that anyone who wants to work for central and local government, from the prime minister down, has got to sign a contract stating that they will be drug free. It would send out a very strong message," he said. Oliver introduced random drug tests in his Scottish force in 1995. The practice has since been adopted by other police forces in Britain, Australia and New Zealand. He dismissed those who opposed drug testing on human rights grounds as "whiners".

Mandatory tests

Earlier this year the London police introduced mandatory testing for amphetamines, ecstasy, cannabis, cocaine, heroin, tranquillisers and sedatives.

Oliver, who helped to establish drug control agencies in Tajikistan and Kyrgyzstan, added: "Many people who work in government will doubtless have kittens because I am quite sure many of them aren't drug free."