Scientists have identified a key gene used by poppies to make morphine, paving the way for better methods of producing the medically important drug, potentially without the need for cultivating poppy fields.

The latest finding follows recent success in engineering brewer's yeast to synthesise opiates such as morphine and codeine from a common sugar, boosting the prospect of "home-brew" drug supply.

But whether making morphine in bubbling vats of yeast will be commercially viable — either for drug companies or criminal gangs — is far from certain, since poppies are very efficient natural factories.