TEHRAN, Iran (AP) -- Iranian opposition leader Mir Hossein Mousavi issued a direct challenge to the country's supreme leader and cleric-led system Wednesday, calling for a mass rally to protest disputed election results and violence against his followers.
Supreme Leader Ayatollah Ali Khamenei had said the night before that Mousavi should pursue his demands through the country's electoral system and Iranians must unite behind their Islamic government, an extraordinary appeal in response to tensions over the presidential vote. But Mousavi appears to have no intention of backing down.
His call on his Web site for a demonstration Thursday came shortly after the country's most powerful military force said that Iranian Web sites and bloggers must remove any materials that "create tension" or face legal action.
"We are after a peaceful rally to protest the unhealthy trend of the elections and realize our goal of annulling the election results," Mousavi said.
He called for "a new presidential election that will not repeat the shameful fraud from the previous election."
Mousavi and his supporters accuse the government of rigging Friday's election to declare hard-line President Mahmoud Ahmadinejad the overwhelming winner.
Their street protests paired with dissent from powerful clerical and political figures have presented one of the gravest threats to Iran's complex blend of democracy and religious authority since the system emerged from the 1979 Islamic Revolution.
The Web became more essential after the government barred foreign media Tuesday from leaving their offices to report on demonstrations on the streets of Tehran.
Mousavi condemned the government for blocking Web sites, saying the government did not tolerate the voice of the opposition.
The Revolutionary Guard, an elite military force answering Khamenei, said through the state news service that its investigators have taken action against "deviant news sites" that encouraged public disturbance and street riots. The Guards are a separate military with enormous domestic influence and control of Iran's most important defense programs. They are one of the key sources of power for the ruling establishment.
The statement alleged that dissident Web sites were backed by Canadian, American and British interests, a frequent charge levied by Iranian hard-liners against their opposition.
"Legal action will be very strong and call on them to remove such materials," it said.
Meanwhile, tensions over the election appeared to be spreading further into the Iranian political and religious classes.
The semiofficial ISNA news agency and the private ILNA news agency reported that scuffles broke out between a reformist lawmaker and a hard-line legislator in an open session of the parliament after they exchanged verbal attacks over the vote results.
The agencies said hardline lawmaker Ruhollah Jani Abbaspour attacked reformist lawmaker Amir Taherkhani after a parliamentary committee probing the protests met Mousavi and the speaker of parliament gave a report on the probe.
Iran's most senior dissident cleric said that the ruling Islamic system had no political or religious legitimacy because of widespread vote fraud.
Grand Ayatollah Hossein Ali Montazeri said in a statement on his Web site that "no sound mind" would accept the results.
"A government that is based on intervening in (people's) vote has no political or religious legitimacy," said Montazeri, who had once been set to succeed Khomeini as supreme leader until he was ousted because of criticisms of the revolution.
The U.S.-based International Campaign for Human Rights in Iran said that several dozen noted figures associated with Iran's reformist movement had been arrested Tuesday, among them politicians, intellectuals, activists and journalists.
Tehran-based analyst Saeed Leilaz, who is often quoted by Western media, was arrested Wednesday by plainclothes security officers who came to his home, said his wife, Sepehrnaz Panahi.
At least 10 Iranian journalists have been arrested since the election, Reporters Without Borders said.
A Web site run by former Vice President Mohammad Ali Abtahi said the reformist had been arrested.
In an attempt to placate the opposition, the main electoral authority has said it was prepared to conduct a limited recount of ballots at sites where candidates claim irregularities.
The recount would be overseen by the Guardian Council, an unelected body of 12 clerics and Islamic law experts close to the supreme leader.
Mousavi charges the Guardian Council is not neutral and has already indicated it supports Ahmadinejad. He and the two other candidates who ran against Ahmadinejad are calling for an independent investigation of voting irregularities.
His representative, reformist cleric Ali Akbar Mohtashamipour, said after a meeting with the Guardian Council Tuesday the number of votes in counted in 70 districts was higher than the population in those districts. He also said many polling stations were closed sooner than scheduled on election night while people were still lining up.
On Tuesday afternoon, the government organized a large rally in Tehran to show it too can bring supporters into the streets. Speakers urged Iranians to accept the results showing Ahmadinejad was re-elected in a landslide Friday.
The appeal for unity failed to calm passions, and a large column of Mousavi supporters - some of them with green headbands and their faces masked against tear gas or to hide their identities - marched peacefully along a central avenue in north Tehran, according to amateur video.
Security forces did not interfere, the witness said, and the protest lasted from about 5 p.m. to 8 p.m. Other witnesses told the AP that about 100 people continued the protest in front of state TV past 9:45 p.m. The witness spoke on condition of anonymity for fear of government reprisal.
Ahmadinejad, who has dismissed the unrest as little more than "passions after a soccer match," attended a summit in Russia that was delayed a day by the unrest in Tehran. That allowed him to project an image as Iran's rightful president, welcomed by other world leaders.