By Ramin Mostafavi and Hashem Kalantari
TEHRAN (Reuters) - Iran will lodge a complaint with the United Nations about what it sees as U.S. President Barack Obama's threat to attack it with nuclear weapons, the foreign ministry said on Sunday.
Obama made clear last week that Iran and North Korea were excluded from new limits on the use of U.S. atomic weapons -- something Tehran interpreted as a threat from a long-standing adversary to attack it with nuclear bombs.
"The recent statement by the U.S. president ... implicitly intimidates the Iranian nation with the deployment of nuclear arms," Iran's Supreme Leader Ayatollah Ali Khamenei said in a televised meeting with military and security officials.
"This statement is very strange and the world should not ignore it since in the 21st century, which is the era of support for human rights and campaigning against terrorism, the head of a country is threatening to use nuclear war."
Foreign ministry spokesman Ramin Mehmanparast told the semi-official Fars news agency Iran would lodge a formal complaint to the United Nations, a move backed by a letter signed by 255 of Iran's 290 members of parliament.
Obama is pressing other global powers to agree to a fourth round of U.N. sanctions against Iran over its refusal to halt nuclear work that the West suspects is aimed at making bombs, a charge Iran denies.
Reflecting fears of attack on its nuclear sites from the United States or its closest Middle East ally Israel, the defense ministry said Iran had started producing a prototype of an advanced anti-aircraft missile system.
"The Mersad air defense system ... is able to destroy modern aircraft at low and medium range altitude," the ISNA news agency on Sunday quoted Defense Minister Ahmad Vahidi as saying.
"The mass production of this product has begun and in the course of the current year a large number of them will be delivered to the armed forces," he said.
While Iran hopes the development of its own system will make it more self-sufficient in weapons defense, it is also urging Russia to resist Western pressure not to deliver the S-300 missile defense system it has ordered.
On Friday, President Mahmoud Ahmadinejad said Iran's nuclear program was "irreversible" despite limits on importing foreign technology and the threat of new sanctions, and he unveiled a prototype of an improved centrifuge which would enrich uranium faster than existing models.
Western analysts say Iran has exaggerated progress in the past to bolster domestic pride about its nuclear program and to improve its bargaining position with major powers.
The head of Iran's Atomic Energy Organization played down the idea that Iran faced big technical hurdles.
"Iran's nuclear issue is not a technical issue ... we are not in a hurry. Second generation centrifuges will be mass produced in the next few months ... in a year we will have prototype cascades of the third generation," Ali Akbar Salehi told ISNA.
(Writing by Robin Pomeroy and Fredrik Dahl; Editing by Elizabeth Fullerton)