Three Iranian Islamic militiamen were killed in an ambush in southern Iran after freeing a hostage, arresting seven suspected kidnappers and seizing a tonne of drugs, Iran's student news agency ISNA said on Monday.
The Basij militiamen, volunteers who see themselves as guardians of revolutionary values, were attacked by an armed group as they led away the captured suspects from a village in the southern province of Kerman.
Three of the militiamen were killed in an hour-long gunbattle, ISNA said.
Heavily armed smugglers often clash with Iranian armed forces along Iran's long, porous border with Afghanistan, the world's top producer of opium, the raw material for heroin.
More than 3,000 members of Iran's armed forces have been killed fighting smugglers since the 1979 Islamic revolution.
Over 175 tonnes of narcotics were seized in Iran in the six months to September, a senior drug enforcement official said last month. Drug smuggling and murder are both punishable by death in Iran.