U.S. President Barack Obama on Friday signed into law an act that bars entry of certain representatives to the United Nations, Xinhua reported.
The act, passed by the U.S. Congress last week, is aimed at blocking Hamid Aboutalebi, Iran's newly appointed ambassador to the UN, from entering the United States.
The law bans any UN envoy from entering the United States if the individual has been engaged in espionage or terrorist activity against the United States and may pose a threat to its national security interests.
Lawmakers sponsoring the act said Aboutalebi should be banned from entry to the United States because he was a member of a militant group that held 52 Americans hostage when it seized the U. S. embassy in Tehran in 1979.
"Acts of espionage and terrorism against the United States and our allies are unquestionably problems of the utmost gravity," Obama said in a statement issued by the White House on Friday.
"I share the Congress's concern that individuals who have engaged in such activity may use the cover of diplomacy to gain access to our Nation," he added.
White House spokesman Jay Carney said a week ago the United States has informed Iran that it will not issue a visa to Aboutalebi.
Iran responded by announcing on Monday that it would sue the United States over the matter. The Islamic republic also said it has a number of options to take against Washington's move.
Aboutalebi said he was only an interpreter for the militant group that seized the U.S. embassy in Tehran on Nov. 4, 1979 and held 52 Americans hostage for 444 days.
Iran said it has no replacement for Aboutalebi, who has served as Iran's ambassador to Australia, the European Union, Belgium, and Italy.
The UN on Monday called the confrontation "a very serious issue. "
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