Drug dealers are increasingly smuggling heroin into the mainland via Hong Kong from drug-production areas of Afghanistan, Iran and Pakistan, a senior customs agent says. They adopted circuitous smuggling routes, hired couriers from different countries and used different concealment methods, according to Ben Leung Lun-cheung, head of customs' drug investigation bureau. The change has prompted local authorities to step up co-operation with mainland and overseas authorities to block smuggling from the so-called 'golden crescent', he said. 'We have to increase the exchange of intelligence, especially with the US Drug Enforcement Agency, as they have a comprehensive worldwide network to stop such illicit trade,' he said. This week officials from around the world will meet at an International Drug Enforcement Conference in Madrid, Spain. Representatives from Hong Kong include Mr Leung and police narcotics bureau officers. Intelligence shows heroin from the 'golden crescent' made up more than 90 per cent of the world's supply in the past two years, Mr Leung said. More than 6,000 tonnes were produced there in 2005. 'The 'golden crescent' has replaced the Golden Triangle of Burma, Thailand and Laos to become the main source of heroin in the past two years,' he said. Customs' seizures rose to 46.9kg last year from 14.6kg in 2005. About 7.6kg was seized in the first four months of this year. Most of 2005's seizures came from the Golden Triangle but last year about two-thirds was from the 'golden crescent'. Customs officers said the majority of heroin seized so far this year also came from the 'golden crescent'. 'This shows that drug smugglers have been exploring new markets in Asia from the 'golden crescent',' Mr Leung said. 'We believe the drug's intended destination was Guangzhou. Hong Kong is among areas such as Shanghai, Thailand and India that are used as a drug-smuggling transition point.'