Police beat the protesters gathered on Baharestan Square with batons and fired tear gas canisters and rounds of ammunition into the air, the witnesses told The Associated Press. They said some demonstrators fought back while others fled to another Tehran plaza, Sepah Square, about a mile (2 kilometers) to the north.
A helicopter could be seen hovering over central Tehran, where a witness told the AP that the area was swarming with hundreds of riot police who were trying to prevent people from gathering even briefly. Thousands more security officers filled the surrounding streets, said the witness, who declined to give his name for fear of government reprisals.
Amateur video posted Wednesday on YouTube showed young men and women throwing rocks and pushing barricades, one blazing, in the street. Others shouted: "Death to the dictator!" The video could not immediately be verified due because of government reporting restrictions.
Severe restrictions on reporters have made it almost impossible to independently verify reports on demonstrations, clashes and casualties. Iran has ordered journalists for international news agencies to stay in their offices, barring them from reporting on the streets.
Supreme leader Ayatollah Ali Khamenei's refusal earlier Wednesday to bow to demands from protesters effectively closed the door to any compromise with the opposition.
The wife of opposition leader Mir Hossein Mousavi was defiant, saying protesters refused to buckle under a situation she compared to martial law.
Mousavi's official Web site had said a protest was planned outside parliament. But the site distanced him from the action, calling it independent and saying it had not been organized by the reformist candidate.
Mousavi's wife, Zahra Rahnavard, a former university dean who campaigned beside him, said on another of his Web sites that his followers had the constitutional right to protest and the government should not deal with them "as if martial law has been imposed in the streets."
She called for the release of all activists and others arrested at protests.
Mousavi, a former prime minister, saw his campaign transform into a protest movement after the government declared that hardline President Mahmoud Ahmadinejad won the June 12 election. Mousavi says the result was fraudulent, and Western analysts who have examined available data on the vote said there were indications of manipulation.
Khamenei has ordered protests to end, leaving Mousavi with the choice of restraining followers or continuing to directly challenge the country's ultimate authority despite threats of escalating force.
"On the current situation, I was insisting and will insist on implementation of the law. That means, we will not go one step beyond the law," Khamenei said on state television. "For sure, neither the system nor the people will yield to pressure at any price." He used language that indicated he was referring to domestic pressures.
He told opposition supporters once again to halt their protests and accused the U.S., Britain and other foreign powers of fomenting days of unprecedented street protests over the vote.
Meanwhile Wednesday, a conservative candidate in the disputed presidential election said 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 elite Revolutionary Guards, moved the cleric-led government one step closer to a final declaration of victory for Ahmadinejad. State TV reported that Ahmadinejad would be sworn in sometime between July 26 and Aug. 19.
Iran also said that it was considering downgrading ties with Britain, which it has directly accused of spying in recent days.
The government accused Britain of using spies to foment the protests and Iran expelled two British diplomats Tuesday. Prime Minister Gordon Brown announced that two Iranian diplomats were being sent home in retaliation.
Foreign Minister Manouchehr Mottaki was asked about the option of reducing diplomatic relations with London after a Cabinet meeting in Tehran.
"We are studying it," Mottaki said, according to state television.
State media have said that at least 17 people have been killed in postelection unrest, including 10 protesters shot during the largest demonstration on Saturday.
Mousavi's supporters flooded the streets of Tehran and other cities after the presidential vote, massing by the hundreds of thousands in protests larger than any since Iran's 1979 Islamic Revolution. Security forces initially stood by and permitted the demonstrations.
Amateur footage of a 27-year-old woman bleeding to death from a gunshot on a Tehran street unleashed outrage at home and abroad.
Despite the heavy security, a few Iranians apparently dared to venture onto the streets to pay tribute to that victim, who has been identified as Neda Agha Soltan.
On Wednesday, smoldering embers of candles were clearly visible on a street corner in central Tehran, where a vigil was held the night before for the slain young woman.
Another opposition figure, reformist presidential candidate Mahdi Karroubi, had called for a day of mourning Thursday for those killed in protests since the election.
Saeed Razavi, the spokesman for Karroubi's campaign, said on the candidate's official Web site later that any mourning was canceled because authorities hadn't given permission.
He said the mourning would be next week at the University of Tehran or near where those slain were buried.
Also, a Mousavi aide confirmed that police had raided offices of a newspaper owned by the candidate and detained 25 editorial employees.
Ali Reza Beheshti said the raid took place Monday evening in central Tehran as editorial members were preparing to relaunch the newspaper, Kalemeh Sabz, or the Green Word. The paper had been absent from newsstands for more than a week.
"Police in uniform raided the office and detained 25 members of the editorial staff," Beheshti said.
Amnesty International said Wednesday it was concerned that arrested demonstrators were at risk of torture or other ill treatment. It urged Iranian authorities to give the detainees access to their families, lawyers and any medical treatment they might need.
"Anyone detained solely for their peaceful expression of their views regarding the outcome of the election should be released immediately and unconditionally," it said.
Two players on Iran's national soccer team, Mehdi Mahdavikia and Ali Karimi, resigned for personal reasons, the semi-official ISNA news agency reported. The pair were among several team members who wore wrist bands in green - the color of Mousavi's opposition movement - before a World Cup qualifying match played last week against South Korea in Seoul.
Associated Press Writer William J. Kole in Cairo contributed to this report.
© 2009 The Associated Press. All rights reserved.
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