Police Chief of South Khorasan province Second Brigadier General Majid Shoja said on Saturday that the consignment was discovered in a passenger bus on route to the northern parts of the country.
Five offenders linked to the illegal haul have been arrested, he added.
The city of Nahbandan is located close to the Afghanistan borders.
Earlier this month, Brigadier General Shoja said the anti-narcotics forces of the province had dismantled 65 drug-trafficking gangs since the beginning of the current Iranian year (March 21, 2019).
According to him, some 43 tons of narcotics have been busted in the province, indicating a 26% increase compared to the corresponding period last year.
The Islamic Republic has been actively fighting drug trades originating from Afghanistan in the past four decades, despite its high economic and human costs. The country has spent more than hundreds of millions of dollars on sealing its borders and preventing the transit of narcotics destined for European, Arab and Central Asian countries.
According to reports, in 2018 alone, Iranian forces carried out 1,557 operations against drug traffickers, seizing approximately 807 tons of different types of narcotic drugs and psychotropic substances.
MNA/IRN83675812