Spanish police say they have prevented the illegal sale of nine military transport helicopters to Iran and have detained eight people, BBC reported.
The operation, which took place in Madrid and Barcelona, led to the arrests of five Spanish businessmen and three Iranian nationals, reports say.
As well as the Bell-212 helicopters, police also found spare parts for export to Venezuela, police said.
Iran is banned from buying attack helicopters under UN sanctions.
The five Spanish businessmen are suspected of trying to export them, while the three Iranians are accused of negotiating the purchase of military material, the AFP news agency reports.
As part of Operation Nam, police raided industrial sites in Madrid and Barcelona, reports say.
The total value of the helicopters and spares was 100m euros ($140m), they said.
Under UN sanctions adopted last year, Iran is banned from buying heavy weapons such as attack helicopters and missiles.