Insurers for the makers of Viagra are facing an embarrassing claim after a £3m consignment of the impotence drug was stolen from Heathrow airport.

Six drums of the drug in powder form was snatched as it was about to be loaded on to a plane for the Catholic country of Puerto Rico.

Pfizer, the makers of Viagra, said the consignment was insured while in transit but declined to reveal its level of cover. However, there is speculation that a reward of £20,000 is being offered for information about the theft.