DUSHANBE, - Border guards in south Tajikistan killed an Afghan smuggler in an overnight operation during which 12 kg (26 lbs) of heroin were seized, the State National Security Committee said Monday.

"During the fight, one smuggler was killed, and 10 others fled the border region. Three sacks with cannabis and 12 kg of heroin were found," the spokesman said.

The operation was jointly conducted by the border guard services of the Commonwealth of Independent States (CIS) since August 4.

During the raid, a total of three Afghan smugglers were killed, one injured and four others detained, with over 20 kg of heroin seized.

The Taliban regime cracked down on opium production in Afghanistan, but since its U.S.-led overthrow in 2001 poppy cultivation has boomed. According to the United Nations, almost 500,000 acres (200,000 hectares) were under cultivation in 2007, and Afghanistan is the world's leading heroin producer.

Most of the heroin sold in Russia is trafficked via Tajikistan, which shares a border with Afghanistan.