Customs officers found the high-voltage engines, each weighing around seven tonnes and imported from South Korea, when they raided an unnamed trading company in Hanover on Wednesday.
Prosecutor Manfred Knothe told Reuters the raids followed a tip-off from an employee of the firm, who said a previous consignment of engines had been dispatched to Iran in December.
Investigators are trying to intercept this batch before it reaches its expected destination of Bushehr, the southern port where Russia is helping Iran to build its first atomic reactor.
The December shipment was worth at least 200,000 euros (140,000 pounds), Knothe said, and authorities have confiscated this amount from the firm.
Iran denies U.S. accusations it is secretly developing an atomic bomb, saying its nuclear industry exists purely to generate electricity, but it remains under investigation by the United Nations nuclear watchdog in Vienna.
Western diplomats say Iran is seeking to acquire equipment for its nuclear industry via front companies whose activities are closely watched by customs officials in Europe.
Prosecutor Knothe said the export of materials for Iranian power plants needed government approval, which had not been given in this case. The offence carries a jail term of up to five years.
Customs investigators also searched the homes of company officials and confiscated computers and other material.
“These are being evaluated, and then we’ll conduct questioning. The proceedings are directed against the head of the export department of this firm,” Knothe said, declining to name it. No one else was currently under suspicion and no arrests had been made, he added.
