(Adds details, Iranian comment, background)
WASHINGTON, April 2 (Reuters) - The United States has told Iran it has deep misgivings about the possibility that Hamid Abutalebi, a veteran Iranian diplomat, may be named to serve as Tehran's new ambassador at the United Nations, the State Department said on Wednesday.
The fact that Abutalebi, who has held key European postings, has been selected by Iranian President Hassan Rouhani as Iran's new ambassador to the United Nations has been well known among U.N. delegations for months, but has not been formally announced or confirmed by Tehran.
The possibility that he may have played a role in the 1979-1981 hostage crisis has outraged some of the U.S. embassy workers held by the Iranians for 444 days as well as some U.S. lawmakers.
"We think this nomination would be extremely troubling," State Department spokeswoman Marie Harf told reporters at her daily briefing. "We have raised our serious concerns about this possible nomination with the government of Iran."
The United States, which severed diplomatic ties with Iran in 1980 during the hostage crisis, is generally required to allow U.N. diplomats to come to New York under its host country agreement with the United Nations. However, it can under limited circumstances refuse to grant visas to such diplomats.
Harf did not explain precisely why the United States found Abutalebi's selection troubling, and did not say how it conveyed this to the Iranian government.
Hamid Babaei, spokesman for Iran's U.N. mission, said: "It has been a usual practice in the Iranian Foreign Ministry to formally announce and appoint ambassadors - to all foreign postings - once all the formalities are completed."
He did not elaborate.
Abutalebi has told Iranian media that he attended the U.N. General Assembly in New York in 1994 as part of the Iranian delegation. He also played down his role during the hostage crisis, suggesting he was just a translator.
Since Rouhani took office in August, Washington and Tehran have taken tentative steps toward improving relations, above all through high-level bilateral negotiations on the sidelines of negotiations on Iran's nuclear program. (Reporting By Arshad Mohammed in Washington and Louis Charbonneau in New York; Editing by Sandra Maler and Mohammad Zargham)