Opposition leader Mirhossein Mousavi said he was "ready for martyrdom", according to an ally, in leading protests that have shaken the Islamic Republic and brought warnings of bloodshed from Iran's Supreme Leader.Mousavi also called on Saturday for a national strike if he is arrested, a witness said. As darkness fell, rooftop cries of Allahu Akbar (God is greatest) sounded out across northern Tehran for nearly an hour, an echo of tactics used in the 1979 Islamic revolution against the Shah.
In an act fraught with symbolic significance, a suicide bomber blew himself up at the mausoleum of the father of Iran's Islamic revolution, Ayatollah Ruhollah Khomeini, while unrest continued across Tehran in defiance of a ban on demonstrations.
Riot police deployed in force, firing teargas, using batons and water cannon to disperse protesters.
Witnesses said 2,000 to 3,000 were on the streets, fewer than the hundreds of thousands earlier in the week, but a clear challenge to Supreme Leader Ayatollah Ali Khamenei who used a speech on Friday to endorse disputed election results that gave hardline President Mahmoud Ahmadinejad a landslide victory.
US President Barack Obama, in the forefront of diplomatic efforts to halt an Iranian nuclear programme the West fears could yield nuclear weapons, urged Tehran to "stop all violent and unjust actions against its own people".
"The Iranian government must understand that the world is watching. We mourn each and every innocent life that is lost," Obama said in a statement.
Defeated candidate Mousavi, a product of the Islamic establishment himself and a former prime minister, made clear he would not back down.
"In a public address in southwestern Tehran, Mousavi said he was ready for martyrdom and that he would continue his path," a Mousavi ally, who asked not to be named, told Reuters by telephone from the Jeyhun street in Tehran.
A witness to the address said Mousavi, centre of protests unprecedented in the 30-year history of the Islamic Republic, appeared to anticipate action against him.
"Mousavi called on people to go on national strike if he gets arrested," the witness told Reuters.
Mousavi demanded the elections be annulled.
"These disgusting measures (election rigging) were planned months ahead of the vote ... considering all the violations ... the election should be annulled," Mousavi said in a letter to the country's top legislative body.
The scale of the demonstrations in Iran, a major oil exporter embroiled in dispute with major powers over its nuclear programme, has taken Iranians and foreign governments by surprise. Hundreds of thousands have taken to the streets in largely peaceful protests, though state media said seven or eight protesters were shot dead earlier in the week.
The attack on the mausoleum of Islamic revolutionary leader Ayatollah Khomeini was likely to inflame passions among Iranians who revere the man who led a movement that overthrew the Western-backed Shah in 1979. It was not clear who carried out the bombing, confirmed by police; but such an incident could be cited by authorities in justifying a crackdown.
The bomber was killed and three others were wounded, according to the English-language Press TV.
Supporters of Mousavi set on fire a building in southern Tehran used by backers of President Ahmadinejad, a witness said.
The witness also said police shot into the air to disperse rival supporters in Tehran's south Karegar street.
Iran's highest legislative body said it was ready to recount a random 10 percent of the votes cast in the June 12 poll to meet the complaints of Mousavi and two other candidates who lost to Ahmadinejad.
Teargas billowed up from Enghelab (Revolution) Square as riot police confronted demonstrators, a witness said.
The Etemad-e Melli party of losing candidate Mehdi Karoubi said plans for a rally had been scrapped for lack of a permit and an ally of Mousavi said the moderate politician had not summoned his followers back to the streets.
Press TV showed footage of a burning bus, without saying where the incident occurred. It also said protesters set fire to a mosque and a number of cars and buses following clashes with police. After dark, calls of Allahu Akbar alternated with chants of "We support you, Mirhossein", ringing out over rooftops.
The 12-man Guardian Council, which must certify the result of the election, announced plans for a partial recount.
"Although the Guardian Council is not legally obliged ... we are ready to recount 10 percent of the (ballot) boxes randomly in the presence of representatives of the three (defeated) candidates," a council spokesman said.
The council had invited Mousavi, Karoubi and a third candidate, Mohsen Rezaie, to raise their complaints at a special session. But only Rezaie, a conservative who is a former Revolutionary Guard commander, attended.
Witnesses said they had seen Basij Islamic militia deploying across Tehran and one resident saw at least three buses full of Basij heading for the capital from the nearby city of Karaj on Saturday, as well as four trucks full of the motorcycles used by Basij militiamen during previous demonstrations.
"If there is any bloodshed, leaders of the protests will be held directly responsible," the white-bearded Khamenei told huge crowds thronging Tehran University for Friday prayers.
Scores of reformists have been arrested and authorities have cracked down on foreign and domestic media.
In a sign of defiance, Mousavi backers took to Tehran rooftops after nightfall on Friday to shout Allahu Akbar (God is greatest), a deliberate echo of tactics in the 1979 revolution. (Reuters)For all the latest business news from the UAE and Gulf countries, follow us on Twitter and Linkedin, like us on Facebook and subscribe to our YouTube page, which is updated daily.
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