The magazine said the suspect was accused of being in contact with a Russian citizen, named as Sergei K., who investigators believed was acting as a buyer for the FSB.
It added that K. had also been in contact in March with the head of a company in the southern German city of Augsburg who was convicted of violating the European Union's embargo on selling weapons to Russia.
In that case, export documents showed that the machinery was to be used in the oil and gas industry. In fact, Der Spiegel reported, they were destined for state company OKB Novator, which makes systems including nuclear-capable ballistic missiles.