Iran warned it would "not hesitate" to strike back at any military action, in a formal complaint to the United Nations over an attack warning made by French President Nicolas Sarkozy.
Sarkozy said last week that Iran's "military nuclear and ballistic ambitions constitute a growing threat that may lead to a preventive attack."
Iran's UN ambassador said in a letter to UN leaders on Thursday that his country would "not hesitate to act in self-defense to respond to any attack against the Iranian nation."
Iran would "take appropriate defensive measures to protect itself," the ambassador, Mohmmad Khazaee, told UN Secretary General Ban Ki-moon and the Security Council, of which France is one of the five permanent members.
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Sarkozy had made "inflammatory remarks and baseless allegations," the envoy added.
"The Islamic Republic of Iran expresses its deep concern over, and strong condemnation of, such a provocative, unwarranted and irresponsible statement against Iran," Khazaee said.
The French leader has been one of the most outspoken critics of Iran in the western alliance which has accused Tehran of seeking a nuclear bomb. The Iranian ambassador again denied the charge.
In an August 31 speech to French ambassadors, Sarkozy did not say which country might carry out the preventive attack.
But he said "Iran refuses to negotiate seriously" and declared that France would work with its allies to build support for tougher international sanctions. The UN Security Council has already passed four rounds of sanctions against Iran over its enrichment programme.