A conservative candidate in Iran's disputed presidential election said Wednesday that he was withdrawing his complaints about voting fraud for the sake of the country, state television reported.

The announcement by Mohsen Rezaie, a former commander of the feared Revolutionary Guards, moved the cleric-led government one step closer to a final declaration of victory for President Mahmoud Ahmadinejad. State TV reported that Ahmadinejad would be sworn in sometime between July 26 and Aug. 19.

Iran's supreme leader declared Friday that Ahmadinejad won fairly but the government appears to be moving in stages toward a final declaration, perhaps to avoid provoking a resurgence of protests by backers of reformist candidate Mir Hossein Mousavi. Mousavi's supporters claim massive fraud tilted the election to Ahmadinejad and want the vote to be canceled and held again.

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The final tally gave 62.6 percent of the vote to Ahmadinejad and 33.75 percent to Mousavi, a landslide victory in a race that was perceived to be much closer. Rezaie came in third.

Khamenei said Tuesday that he had agreed to extend the deadline for registering complaints about the election by five days. The Guardian Council, Iran's top electoral body, initially said it would make it's final decision on whether to validate the election result by Wednesday.

Mousavi has said little and remained out of the public eye as the government flooded the streets of Tehran with police and pro-government militia to deter further protests. It has quietly been arresting reformist activists and others, according to human rights group outside the country.

Government tallies have shown that at least 627 people have been arrested in Tehran. Some state media have reported 17 protesters killed by security forces. Other state reports give the number as 27, said Hadi Ghaemi, director of the New York-based International Campaign for Human Rights in Iran.

Ghaemi said he believes the number of dead is much higher, based on conversations with hospital workers, witnesses and relatives of victims in Iran.

Another opposition figure, reformist presidential candidate Mahdi Karroubi, called for a day of mourning for those killed in protests since the election. Some social networking sites suggested that the mourning would take place Thursday.

Mousavi's informal spokesman outside Iran, filmmaker Mohsen Makhmalbaf, said in Rome that even if Ahmadinejad manages to govern for the next four years, "he will not have one day of quietness," with protesters resorting to general strikes and civil resistance.

State-run TV confirmed the arrest of Iason Athanasiadis, a Greek national reporting for the Washington Times. Ghaemi said it was the first known arrest of a journalist who did not hold Iranian citizenship. He portrayed it as significant escalation of the attempt to repress independent reporting by a government that had shied away from arresting foreign journalists in recent years.

A number of journalists have been detained since the protests began, although there have been conflicting accounts. The Paris-based Reporters Without Borders put the figure at 34. The New York-based Committee to Protect Journalists said 13 were in custody, including Newsweek correspondent Maziar Bahari.

There were no reported demonstrations Tuesday and protesters have been resorting to more subtle ways of challenging the outcome of the presidential election: holding up posters, shouting from rooftops and turning on car headlights.

"People are calmly protesting, more symbolically than with their voices," a Tehran resident said in a telephone interview, speaking on condition of anonymity for fear of government retribution.

President Barack Obama hardened his rhetoric on the crackdown, saying Tuesday the world was "appalled and outraged"

"I have made it clear that the United States respects the sovereignty of the Islamic Republic of Iran, and is not interfering in Iran's affairs," Obama said. "But we must also bear witness to the courage and dignity of the Iranian people, and to a remarkable opening within Iranian society. And we deplore violence against innocent civilians anywhere that it takes place."

Obama had been avoiding harsh condemnation of Iran's government, which often labels domestic unrest as the work of foreign agents.

Iran expelled two diplomats from Britain — a nation it bitterly accuses of meddling and spying — and Britain in turn sent two Iranian envoys home. There was no immediate word Wednesday on any Iranian reaction to the speech by Obama, who had been trying to warm relations with the Islamic Republic.

Iran's expulsions came a day after Britain sent home a dozen dependents of diplomatic staff because of the unrest.

About 100 hard-line students protested outside the British Embassy in Tehran, where they burned U.S., British and Israeli flags, pelted the building with tomatoes, and chanted: "Down with Britain!" and "Down with USA!" state TV reported.

Iran also accused U.N. Secretary-General Ban Ki-moon of interfering in its domestic affairs.

Ban told the Associated Press on Tuesday that the "Iranian government must stop the arrest of these people and protect the civilians, and also protect the freedom of assembly, freedom of expression and freedom of information."

Iran's leaders have ruled out a revote, saying they found no major fraud, even though the Guardian Council has acknowledged irregularities in 50 of 170 districts. The council said the discrepancies were not widespread enough to affect the outcome.

Iran has 46.2 million eligible voters, one-third of them under 30. The huge margin of victory for Ahmadinejad went against the expectation that the record 85 percent turnout would help Mousavi.