A suicide bomber killed five policemen and wounded four others in an attack on a counternarcotics force in southern Afghanistan on Thursday morning, a police official said. Kamal Uddin said the bomber attacked the patrol in Lashkar Gah, the capital of Helmand province, a major drug producing province. Uddin is the provincial deputy police chief. Afghanistan is the world's largest producer of opium, the main ingredient in heroin. The Afghan drug trade accounts for 90 percent of worldwide production. The UN estimated last year that up to $500 million from the illegal drug trade flows to Taliban fighters and criminal groups.