* Mousavi says ready for 'martyrdom' - ally * Mousavi calls for national strike if he arrested-witness * Suicide bomber at Khomeini shrine * Police fire teargas, use batons, water cannon EDITORS' NOTE: Reuters and other foreign media are subject to Iranian restrictions on their ability to report, film or take pictures in Tehran. (Adds Obama call to Iranian government) By Parisa Hafezi TEHRAN, June 20 (Reuters) - 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 said on Saturday he did not seek confrontation with the Islamic establishment, but was quoted by a witness as calling for a national strike if he is arrested. "We are not against the Islamic system and its laws but against lies and deviations and just want to reform it," he said on his website. As darkness fell, rooftop cries of Allahu Akbar (God is greatest) sounded across northern Tehran for nearly an hour, an echo of tactics used in the 1979 Islamic revolution. 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 scattered groups of several hundred had taken to the streets around Tehran -- fewer than the hundreds of thousands earlier in the week, but a clear challenge to Supreme Leader Ayatollah Ali Khamenei who on Friday endorsed disputed election results giving hardline anti-Western President Mahmoud Ahmadinejad a landslide victory. United States 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. Mousavi, a product of the Islamic establishment himself and a former prime minister, appeared to pledge loyalty to the Islamic state, but made clear he would not back down over his claim of victory in the June 12 election. "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. MAUSOLEUM ATTACK 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. He said in a statement posted on his website the authorities must allow peaceful protest. "Those who do not allow such gatherings will be responsible for its dangerous consequences. "I will never allow this beautiful green wave to risk its life because of me. Be sure that I will always be at your side." The scale of the demonstrations in Iran, a major oil exporter and important factor in regional stability, 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. WAFTS OF TEARGAS 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 random recount of 10 percent of the ballot boxes. Scores of reformists have been arrested and authorities have cracked down on foreign and domestic media. (Writing by Ralph Boulton)
EDITORS' NOTE: Reuters and other foreign media are subject to Iranian restrictions on leaving the office to report, film or take pictures in Tehran Protesters run from tear gas fired by ...
