Iranian Law Enforcement officials announced on Monday that police units in the Northern Qazvin province have disbanded 15 major drug rings and seized large volumes of narcotics in the last 6 months. \"During the first six months of the current (Iranian) year (March 21-September 22) 15 drug-trafficking networks have been disbanded in the province and 428 drug-traffickers and dealers have been arrested, thanks to the efforts made by Qazvin province\'s police forces,\" Commander of the Anti-Drug Police Squads of Qazvin Qassem Qiasvand announced on Monday. The commander mentioned that police troops have seized a total volume of 1,024kg of different types of narcotics during the said period, and added that drug discoveries show a 127% increase compared with the same period last year. Qiasvand further said that seizures included 806kg of opium, 142kg of hashish, 11kg of heroin and 64kg of other types of illicit drugs. He further warned that drug-traffickers are trying to replace conventional narcotics with synthetic drugs since the latter is cheaper and can be transferred easily. Synthetic drugs have recently been smuggled and distributed in Iran by drug-traffickers who seek to change addiction behaviors in the country and redirect addicts\' tendency from conventional drugs, such as opium, heroin and hashish, to those narcotics mostly prevalent in the West, like cocaine, crack, crystal meth and LSD. Iran leads international efforts in fighting drug networks and narcotic traffickers. According to the statistical figures released by the UN, Iran ranks first among the world countries in preventing entry of drugs and decreasing demand for narcotics.