highly sensitive new equipment to conduct extremely thorough searches on travellers and if they find any amount - no matter how minute - it will be enough to attract a mandatory four-year prison sentence." Mrs Wolthuizen added: "We even have reports of the imprisonment of a Swiss man for 'possession' of three poppy seeds on his clothing after he ate a bread roll at Heathrow. Held: A campaign is underway to secure the release of Cat Le-Huy from a Dubai jail "What many travellers may not realise is that they can be deemed to be in possession of such banned substances if they can be detected in their urine or bloodstream, or even in tiny, trace amounts on their person." Only two months after Mr Brown was stopped economics graduate Robert Dalton was detained in almost identical circumstances. Mr Dalton, from Gravesend, on Kent was with two friends when he was stopped and asked to empty his pockets. Officials found 0.03g of cannabis in a small amount of fluff. He is currently on trial and if convicted, is likely receive a four-year prison sentence. Last night his brother Peter, 26, told how it took 24 hours to find out why he had been stopped. "As we understand, the amount of cannabis was barely visible to the human eye and was at the bottom of the pocket of an old pair of jeans. "He's not a drug user, but he goes clubbing and the speck was so small." Last week Cat