Washington is calling on Tehran to release three Iranian opposition leaders who have been under house arrest since 2011 without being formally charged with any crime.
Zahra Rahnavard (L), Mir Hossein Musavi (C) and Mehdi Karrubi
The U.S. State Department issued the call on February 14 - marking the third anniversary of the detention of former presidential candidates and opposition leaders Mehdi Karrubi and Mir Hossein Musavi, and Musavi's wife - women's rights advocate Zahra Rahnavard.
Karrubi and Musavi ran in Iran's disputed 2009 presidential election, in which former President Mahmud Ahmadinejad was declared the official winner.
They were placed under house arrest in February 2011 after calling for demonstrations in support of Arab Spring uprisings.
Earlier on February 14, the human rights group Amnesty International also called on Iranian authorities to "immediately end the arbitrary detention" of the opposition figures.
It said they have been held without charge or trial for three years, with no possibility to challenge the lawfulness of their detention.
Amnesty said it was concerned about the health conditions of the three figures, all of whom are elderly and suffering from physical ailments.
Based on reporting by RFE/RL