TEHRAN/WASHINGTON President Mahmoud Ahmadinejad said on Thursday Iran was close to enriching uranium nearly pure enough for atomic bombs but the United States was dismissive, saying he spoke to rally government supporters on the Islamic revolution's 31st anniversary.
Ahmadinejad told a vast, flag-waving crowd of government supporters in central Tehran's Azadi (Freedom) Square that Iran could now enrich uranium to more than 80 percent purity, coming close to levels experts say is needed for a nuclear bomb, although he again denied any such intention.
"The Iranian nation is brave enough that if one day we wanted to build nuclear bombs we would announce it publicly without being afraid of you," Ahmadinejad said, addressing Iran's Western enemies.
He told the crowd: "When we say that we don't build nuclear bombs, it means that we won't do that because we don't believe in having it."
The United States does not believe Iran is capable of enriching uranium to that degree, White House spokesman Robert Gibbs said in response.
"Iran has made a series of statements that are ... based on politics, not on physics," he told reporters.
In Vienna, a think-tank tracking nuclear proliferation said that "while Iran may take longer than expected to make sufficient weapons-grade uranium, few believe it will fail in that effort."
The report by David Albright and Christina Walrond of the Institute for Science and International Security said international sanctions had slowed Iran's progress but not stopped it.
Iranian State television said "tens of millions of people" rallied to support the revolution across the country of 70 million, which is facing its worst domestic crisis in three decades after a disputed presidential election.
Opposition supporters have coalesced around the reformists who lost to Ahmadinejad in the election last June, and refused to yield to government demands to halt protests.
SECURITY FORCES FIRE SHOTS
State television showed footage of hundreds of thousands of people, some carrying Iranian flags and pictures of Supreme Leader Ayatollah Ali Khamenei, walking to the square.
Khamenei later thanked the Iranian people for turning out in such numbers.
An opposition website, Iran's Green Voice, said security forces fired shots and teargas at supporters of opposition leader Mirhossein Mousavi staging a Tehran counter-rally on the anniversary of the revolution that toppled the Shah.
The opposition Kaleme website said plainclothes security officers beat Mousavi's wife Zahra Rahnavard with batons when she tried to attend the rally, but she "was rescued by Mousavi's supporters."
A third website, Jaras, said security forces attacked another opposition leader, Mehdi Karoubi, and moderate former president Mohammad Khatami. It said the windows of Karoubi's car were smashed but he was not seriously hurt.
Jaras said clashes continued in Tehran's Ariashahr district and gunshots were heard.
Jaras said at least 100 mainly young protesters were detained in the northeastern city of Mashhad, and there were some "limited" clashes with security forces. It said more than 20 people were detained in the southern city of Shiraz, as anti-riot police sought to prevent protesters from gathering.
The reports could not be verified independently because journalists working for foreign media were escorted to Azadi Square and were not at liberty to cover opposition rallies.
There were no reports of the kind of violence that erupted in late December, when eight people were killed in clashes between security forces and opposition supporters.
Neither side has shown much appetite for compromise since the vote, which the opposition says was rigged to secure Ahmadinejad's re-election. The authorities insist it was fair.
Since June, thousands of people protesting against the conduct of the vote have been arrested. Most have since been freed, though more than 80 people have been jailed for up to 15 years, including several senior ex-officials. In January, Iran hanged two people sentenced to death in post-vote trials. At least nine others are appealing such sentences.
The country faces growing Western calls for a new round of targeted United Nations sanctions against it after Ahmadinejad this week ordered the start of higher-grade uranium production.
Iran says it moved to produce the 20 percent enriched uranium for a Tehran research reactor making medical isotopes out of frustration at failure to reach agreement on a uranium exchange with world powers.
"By God's grace ... it was reported that the first consignment of 20 percent enriched uranium was produced and was put at the disposal of the scientists," Ahmadinejad said. "In the near future we will treble its production."
Iran had previously purified the fuel to just 3.5 percent, the level required for a nuclear power plant. Western experts say the jump to 20 percent is a technical leap toward enriching uranium to the 90 percent-plus needed for a nuclear bomb.
Iran's newly launched 20 percent nuclear fuel production was going "very well," the Islamic Republic's Atomic Energy Organization chief told Reuters in an interview on Thursday.
Ali Akbar Salehi said Iran had the capacity to enrich uranium up to a level of 100 percent. "But we never had the intention and we do not have the intention to do so, unless we need (to)," Salehi said.
The West accuses Iran of covertly trying to build nuclear bombs. Iran, the world's fifth-largest crude oil exporter, says its nuclear facilities are part of a peaceful energy program and it would retaliate for any attack on them.
(Additional reporting by Hossein Jaseb, Ramin Mostafavi and Reza Derakhshi, Writing by Mark Trevelyan; Editing by Philip Barbara and Alan Elsner)