Four men arrested in Germany are scheduled to appear in court on Wednesday on charges of breaking Germany's sanctions against Iran's nuclear program.

The four men, one German citizen and three dual Iranian-German citizens, are suspected of supplying parts to help build Iran's heavy water reactor via front companies in Turkey and Azerbaijan.

"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," the prosecutors who lead the investigation and arrests 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."

Iran insists that it is developing nuclear capabilities for peaceful reasons, but that did not stopped the United Nations from slapping six rounds of sanctions since 2006 on Iran against its key oil sector. In January, the European Union also passed measures against Iran's oil sector, and in March the EU disconnected Iranian banks from the Society for Worldwide Interbank Financial Telecommunication, the world's central banking hub.

Prosecutors also said it took 90 customs officers to lead the search and arrest of the four men in their homes in Hamburg, Oldenburg, and Weimar, Germany.

The four men were identified as Kianzad Ka., Gholamali Ka., Hamid Kh. and Rudolf M. (German privacy laws prevent their full names from being released).

According to the BBC, a possible fifth suspect has been arrested but has not been named.