German officials arrested four people Wednesday on suspicion that they supplied Iran with parts needed to build a nuclear reactor, in violation of the country's trade embargo on such items.
The German man and three German-Iranian dual nationals were suspected of illegally shipping valves through front companies in Turkey and Azerbaijan in 2010 and 2011 in deals worth millions of euros, prosecutors' spokesman Marcus Koehler told NBC News.
Suspects Rudolf M., a German, and dual citizens Kianzad Ka., Gholamali Ka. and Hamid Kh., were taken into custody on Wednesday, Koehler said. The suspects' full names were not made available.
Some 90 customs agents and prosecutors searched homes and businesses in Hamburg, Oldenburg and Weimar.
The involvement of German federal authorities reflected just how seriously the case was being taken, Koehler added.
NBC's Richard Engel and Ali Arouzi report on the escalating tension between the two nations.
"The federal prosecutor's office is only responsible for such cases when they have a special significance," he told NBC News.
Six world powers -- Germany, the United States, Russia, China, France and Britain -- have sought to persuade Iran to scale back its nuclear program, which they fear is aimed at developing weapons, through intensifying economic sanctions and diplomacy.
Defense Secretary Leon Panetta now believes there's a strong possibility that Israel will attack Iran in an attempt to thwart Tehran's nuclear ambitions, according to U.S. officials. NBC's Richard Engel reports.
Tehran maintains its program serves peaceful purposes only.
Reuters contributed to this report.
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