Iran's Judiciary Spokesman on Tuesday said a German prisoner was freed on Monday in return for an Iranian national facing extradition from Germany to the United States.

The unidentified German citizen had been serving a 3-year sentence "for a while" for "taking photographs in sensitive locations," Gholamhossein Esmaili told reporters and added that Iran had informed Germany the prisoner would be freed "on the condition that they do not extradite our citizen to the United States".

Ahmad Khalili was freed on Sunday and flew home with Foreign Minister Mohammad Javad Zarif who was in Germany to attend a security conference in Munich last week.

According to the Iranian Foreign Ministry Spokesman Abbas Mousavi the U.S. had requested his arrest and extradition.

Khalili had been detained in Germany for violation of U.S. sanctions. No comment has so far been made by Iranian, German or U.S. officials about the exact nature of the charges against Khalili or his activities.

Iranian state-media usually report extensively on prisoners returning home but Khalili's arrival was only announced the day after his arrival by the Foreign Ministry Spokesman in a statement on Monday.

Mousavi said Khalili was freed after "intensive diplomatic negotiations" and with "the cooperation of Iran's Judiciary and the Revolutionary Guard's Intelligence Organization".

An individual of the same name was arrested in Spain in 2011 for military purchases. Media affiliated to the Revolutionary Guard at the time said he was an official in charge of procurement of military equipment for the ministry of defense.

The said individual was freed sometime during 2011 by posting a 30,000-euro bail. No further information was ever published about his case.