State television reported that the Guardian Council presented the conclusion in a letter to the Interior Minister following a recount of a what was described as a randomly selected 10 percent of the almost 40 million ballots cast June 12.
The "meticulous and comprehensive examination" revealed only "slight irregularities that are common to any election and needless of attention," Guardian Council head Ahmed Jannati said in a letter, according to the state TV channel IRIB.
Opposition leader Mir Hossein Mousavi claims he, not incumbent President Mahmoud Ahmadinejad, was the rightful winner and has called for a new election, something the government has repeatedly said it will not do. "From today on, the file on the presidential election has been closed," Guardian Council spokesman Abbas Ali Kadkhodaei said on state-run Press TV.
Mousavi supporters have taken to the streets in protest after the election, outraged by official results that gave Ahmadinejad the victory by a roughly 2-1 margin. Police and the feared Basij militia have taken increasingly harsh measures against the demonstrators, prompting widespread international criticism.
The recount conducted Monday had appeared to be an attempt to cultivate the image that Iran was seriously addressing fraud claims, while giving no ground in the clampdown on opposition.
Supreme leader Ayatollah Ali Khamenei and the Council already had pronounced the results free of major fraud and insisted that Ahmadinejad won by a landslide. And even if errors were found in nearly every one of the votes in the recount Ahmadinejad, according to the government's count, still would have tallied more votes than Mousavi.
U.S. Secretary of State Hillary Rodham Clinton on Monday questioned the recount's utility.
"They have a huge credibility gap with their own people as to the election process. And I don't think that's going to disappear by any finding of a limited review of a relatively small number of ballots," she told reporters in Washington. Asked if the United States would recognize Ahmadinejad as Iran's legitimate president, she said "We're going to take this a day at a time."
News of the partial recount comes as Ahmadinejad on Monday ordered an investigation of the killing of a young woman on the fringes of a protest. Widely circulated video footage of Neda Agha Soltan bleeding to death on a Tehran street sparked outrage worldwide over authorities' harsh response to demonstrations.
Ahmadinejad's Web site said Soltan was slain by "unknown agents and in a suspicious" way, convincing him that "enemies of the nation" were responsible.
The developments appear to show that Iran's leaders are concerned about international anger over the election and opposition at home that could be sustained and widespread -- but is trying to portray the country as victimized by foreign powers.
Throughout the postelection turmoil, Iranian officials have bristled at even mild criticism from abroad. But the tensions escalated Sunday when Iran announced it had detained nine local employees of the British Embassy on suspicion of fomenting or aiding protests. Iranian Foreign Ministry spokesman Hasan Qashqavi said Monday that five of the Iranian embassy staffers had been released and the remaining four were being interrogated.
Intelligence Minister Gholam Hossein Mohseini Ejehi Monday claimed he had videotape showing some of the employees mingling with protesters, and said the fate of those who remain in custody now rests with the court system in a country where supreme leader Ayatollah Ali Khamenei's word is law.
Qashqavi played down the dispute, saying officials were in written and verbal contact with British Foreign Secretary David Miliband and that Iran had dismissed the idea of downgrading relations, saying "Reduction of diplomatic ties is not on our agenda for any country, including Britain."
The statement did not mollify Britain, whose Prime Minister Gordon Brown said Monday that Iran's actions were "unacceptable, unjustified and without foundation."
Italian Premier Silvio Berlusconi said Group of Eight leaders meeting next week in Italy will discuss possible sanctions against Iran.
Ejehi boasted that Iran had overcome attempts at an uprising like the Velvet Revolution, the peaceful 1989 mass demonstrations that brought down then-Czechoslovakia's Communist regime. "I can surely say that such a thing will not happen in our country. But if the question is whether the enemy was after this or not, the answer is that it certainly was," he said in remarks shown on state television. The regime has implicated protesters and even foreign intelligence agents in Soltan's death. But an Iranian doctor who said he tried to save her told the BBC last week she apparently was shot by a member of the volunteer Basij militia. Protesters spotted an armed member of the militia on a motorcycle, and stopped and disarmed him, Dr. Arash Hejazi said.
Basij commander Hossein Taeb on Monday alleged that armed impostors were posing as militia members, Iran's state-run English-language satellite channel Press TV reported.
Authorities have cracked down hard on dissent, most recently on Sunday, when riot police clashed with up to 3,000 protesters near the Ghoba Mosque in north Tehran. It was Iran's first major post-election unrest in four days.
Witnesses told The Associated Press that police used tear gas and clubs to break up the crowd, and said some demonstrators suffered broken bones. They alleged that security forces beat an elderly woman, prompting a screaming match with young demonstrators who then fought back. North Tehran is a base of support for opposition Mousavi.
The reports could not be independently verified because of tight restrictions imposed on journalists in Iran.
Also Monday, the human rights watchdog organiization Amnesty International expressed concern that prominent opposition figures arrested since the protests broke out could be subjected to torture. In a statement, it said three senior political leaders are believed to be held in a prison run by the Intelligence Ministry where torture reportedly is widely used.