"The four, one German and three German-Iranian dual citizens, are accused of supplying parts used for Iran's nuclear program, breaking imposed sanctions.
German police have arrested four men suspected of delivering valves for a heavy water reactor to Iran and breaking an embargo on such exports to the Islamic Republic imposed over its disputed nuclear program.
Prosecutors said some 90 customs officers arrested the men - one German and three with dual German and Iranian citizenship, at their homes in the northern cities of Hamburg and Oldenburg and the eastern town of Weimar, and searched flats and offices.
"In 2010 and 2011 the suspects are believed to have helped in the delivery of special valves for the construction of a heavy water reactor in Iran and therefore to have broken the Iran embargo," prosecutors said in a statement on Wednesday.
"The deliveries were part of an order worth several million euros which Iran was trying to use to secure the necessary valve technology to make a heavy water reactor," said the prosecutors.
The men were therefore suspected of breaking Germany's law on foreign trade and breaching military weapons controls.
Prosecutors’ spokesman Marcus Koehler said suspects Rudolf M., a German, and dual citizens Kianzad Ka., Gholamali Ka. and Hamid Kh., were taken into custody on suspicion they had illegally supplied valves needed for the reactor’s construction in 2010 and 2011.
The three, whose last names were not released in accordance with German privacy laws, are accused of supplying the parts to Iran through front companies in Turkey and Azerbaijan.
Iran has been hit with several rounds of UN sanctions, plus tougher measures imposed by the European Union and United States, since 2006 due to its refusal to suspend enrichment of uranium, a process that yields fuel for nuclear power stations but also nuclear bombs, depending on the level of refinement.
Iran, the world's No. 5 oil exporter, says it does not want to build a bomb but rather needs nuclear energy for electricity to meet the needs of a rapidly expanding population.
Earlier, Standard Chartered Plc reached a e340 million settlement with New York's bank regulator for transactions linked to Iran although the bank may still face investigations into transactions by other U.S. agencies.
The New York Financial Services Superintendent had this month accused Standard Chartered of breaking U.S. sanctions on Iran, saying it had hidden Iran-linked transactions worth a total of e250 billion from regulators."