Iran has no plans to name a new diplomat to the United Nations, its Foreign Ministry said Saturday, April 12, after the United States blocked its pick in a rare rebuke that could stir fresh animosity at a time when the two countries have been seeking a thaw in relations, the Associated Press reports.

The Obama administration said Friday that the U.S. had informed Iran it would not grant a visa to Hamid Aboutalebi, a member of the group responsible for the 1979 takeover of the U.S. Embassy in Tehran. While U.S. officials had been trying to persuade Iran to simply withdraw Aboutalebi's name, the announcement amounted to an acknowledgement that those efforts had not been successful.

"The Ministry of Foreign Affairs is pursuing this issue through anticipated legal channels at the UN," Deputy Foreign Minister Abbas Araghchi was quoted as saying by Iran's semiofficial Mehr news agency. "We have no choice to substitute Mr. Aboutalebi."

Aboutalebi is alleged to have participated in a Muslim student group that held 52 Americans hostage for 444 days during the embassy takeover. He has insisted his involvement in the group Muslim Students Following the Imam's Line was limited to translation and negotiation. Iran says he is one of the country's best diplomats, and that he previously received a U.S. visa. He has already served at Iranian diplomatic missions in Australia, Belgium and Italy.