U.S. Secretary of State Hillary Clinton said her government was concerned by reports of Iran's continued repression of its own people, especially those of "diverse faiths."
"We are particularly concerned by reports that Christian pastor Youcef Nadarkhani is facing execution on charges of apostasy for refusing to recant his faith," Clinton said. "This comes amid a harsh onslaught against followers of diverse faiths, including Zoroastrians, Sufis and Baha'is."
Christian Solidarity Worldwide said it fears Nadarkhani will be put to death despite reports that his sentence was annulled.
Nadarkhani was arrested in October 2009 while attempting to register his church. He was found guilty of apostasy -- abandoning Islam -- in September 2010 and was sentenced to death.
Nadarkhani was born to Muslim parents but didn't practice the faith. He converted to Christianity in 1996 when he was 19.
"The United States stands with the international community and all Iranians against the Iranian government's hypocritical statements and actions and we continue to call for a government that respects the human rights and freedom of all those living in Iran," added Clinton.