The White House says it has told Iran it will have to find a different envoy for the United Nations and not one who participated in the 1979 taking of 52 U.S. hostages in Tehran.
White House spokesman Jay Carney Tuesday said Tehran has been informed that the selection of Hamid Abutalebi is "not viable."
American officials object to Abutalebi because of his alleged participation in a Muslim student group that held 52 Americans hostage for 444 days in the 1979 seizure of the U.S. Embassy in Tehran.
Abutalebi has worked as Iran's ambassador to Belgium, the European Union, Italy and Australia. He has insisted that his involvement in the group Muslim Students Following the Imam's Line was limited to translation and negotiation.
The hostage crisis was a key moment in the lives of many senior Iranian political figures and led to diplomatic relations being cut between Washington and Tehran.