A demonstration near Iran's parliament turned into a "bloodbath" Wednesday, a source in Tehran told CBSNews.com.
Thousands gathered at the parliament building for a silent protest, reported the unnamed source. But scene took a violent turn when more than 1,000 police and Basij militia arrived to disperse the crowd.
"It turned into a bloodbath ... they threw some people off the bridges...after the Basijis came, they began to use tear gas, sticks and shooting," he said.
Earlier Wednesday, Iran's supreme leader said that the government would not give in to pressure over the disputed presidential election, effectively closing the door to compromise with the opposition.
But reformist leader Mir Hossein Mousavi's official Web site said that a protest was planned nonetheless outside Iran's parliament Wednesday afternoon. It distanced him at the same time, calling the demonstration independent and saying it had not been organized by Mousavi.
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Mousavi's mixed messages about the demonstration reflected the dilemma facing the unlikely opposition leader, a longtime supporter of Iran's government thrust to the head of a pro-democracy protest movement.
Supreme Leader Ayatollah Ali 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.
Other reports of the violent crackdown flooded the Internet Wednesday, though accounts of the clashes could not be confirmed.
CNN interviewed a female witness to the clashes who hysterically described the violence.
"They beat a woman so savagely that she was drenched in blood," she said.
The woman also said she saw "security forces shooting on people."
There were rumors a young girl was taken to the hospital after being shot by security forces, though that report could not be confirmed.
State media continued to insist Wednesday that the dissent was being stoked by outside groups bent on destabilizing the country, including the CIA. State TV also reports that two terrorists have been arrested in connection with the protests.
Mousavi's wife, Zahra Rahnavard, a former university dean who campaigned beside her husband, said on one 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.
Meanwhile, Tehran's mayor is calling for Iranian authorities to legalize peaceful opposition protests, according to a report on Iran's PressTV.
In an interview on Iranian TV, Mohammad Baqer Qalibaf said easing restrictions on rallies would prevent "saboteurs who draw weapons and kill people."
Mousavi, a former prime minister, saw his campaign transform into a protest movement after the government declared that hardline President Mahmoud Ahmadinejad was the overwhelming winner of the June 12 election.
Mousavi said the result was fraudulent and Western analysts who have examined available data on the vote said there were indications of manipulation.
His supporters flooded the streets of Tehran and other cities after the 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.
Khamenei ordered an end to protests on Friday and security forces beat protesters and fired tear gas and water cannons at rallies the next day. At least 10 protesters were shot, according to official tallies.
An unconfirmed report stated that the country's powerful, 86-member Assembly of Experts - headed by former president Akbar Hashemi Rafsanjani - is split in its support for Khamenei and Ahmadinejad. However, neither is expected to lose their positions.
Khamenei's comments come on the heels of a conservative candidate 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 President Mahmoud Ahmadinejad. State TV reported that Ahmadinejad would be sworn in sometime between July 26 and Aug. 19.
State media have said that at least 17 people have been killed in post-election unrest. 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, smouldering 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, 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.
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 colour of Mousavi's opposition movement - before a World Cup qualifying match played last week against South Korea in Seoul.
In weighing the direction of the protests, Mousavi appeared to be trying a compromise approach: He has made no public appearances since Thursday but he has issued strongly worded statements calling for supporters to continue demonstrations.
The protest set for Wednesday could set the stage for new confrontation.
"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 give in to pressures at any price." He used language that indicated he was referring to domestic pressures.
He told opposition supporters to halt their protests and blamed the U.S., Britain and other foreign powers for instigating unrest.
Iran also said that it was considering downgrading ties with Britain, which it has accused of spying and fomenting days of unprecedented street protests over the vote.
The government accused Britain of using spies to foment the unprecedented street 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.
On Tuesday, President Obama hardened his rhetoric on the crackdown, saying 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," Mr. 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."
Mr. 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 Mr. Obama, who had been trying to warm relations with the Islamic Republic.