The United States and Iran are locked in a new dispute over Tehran’s proposed ambassador to the United Nations. The Senate has voted to bar Hamid Aboutalebi from entering the United States because he allegedly belonged to the group behind the 1979 hostage crisis in Tehran. The measure would prevent Aboutalebi from taking up his new post at U.N. headquarters in New York City. At the White House, Press Secretary Jay Carney said the United States has informed Iran of its opposition.

White House Press Secretary Jay Carney: “Well, we share the Senate’s concerns regarding this case and find the potential nomination extremely troubling. The U.S. government has informed the government of Iran that this potential selection is not viable. The legislation passed by the Senate underscores just how troubling this potential nomination would be.”

Carney stopped short of saying the Obama administration would bar Aboutalebi’s entry into the country. He has previously served as Iran’s ambassador to Belgium, Italy, Australia and the European Union, and has denied playing a direct role in the hostage crisis. The spat comes as a new round of talks over Iran’s nuclear program are resuming in Vienna.