Monday Iranian opposition leader Mirhossein Mousavi's car was attacked by "plainclothes men" on motorbikes and one member of his entourage was injured, the reformist Kaleme website reported.
Kaleme said the incident happened when Mousavi was on his way back to Tehran after attending the funeral of leading dissident cleric Grand Ayatollah Hossein Ali Montazeri in Qom. It said the car's back window was smashed in the attack.
Kaleme said the group on motorbikes insulted Mousavi and those accompanying him and several times stopped his motorcade and prevented it from resuming its journey.
"On the way back from Qom to Tehran before noon ... a group of plainclothes men riding motorcycles attacked the car carrying Mousavi, as a consequence of which one member of Mousavi's entourage was injured," Kaleme said, Ynetnews reports.
It was also reported, hundreds of thousands of opposition protesters openly challenged the authority of Iran's supreme leader, Ayatollah Ali Khamenei, today by mourning the death of a dissident cleric who had questioned Khamenei's fitness to rule.
The mass turnout in Qom for the funeral of Grand Ayatollah Hossein-Ali Montazeri, who died on Sunday, aged 87, came just a day after Khamenei had dismissed him as a figure who had failed "a big test" and ordered a security clampdown to deter mourners from paying their respects.
Instead, the event turned into the opposition Green Movement's biggest show of strength in months. The sheer numbers – including many wearing the opposition's signature colour of green – seemed to confirm the Islamic regime's fears that Montazeri's death could provide a fresh spark for the simmering discontent over President Mahmoud Ahmadinejad's hotly disputed re-election last June.
The authorities were powerless to stop a gathering officially meant to mourn the passing of one of the pillars of the 1979 Islamic revolution. But its overtly political nature was displayed by the presence of Mir-Hossein Mousavi and Mehdi Karroubi, the two defeated reformists from last summer's poll, guardian.co.uk reports.
Meanwhile, this year's antigovernment protests, the biggest since the Islamic revolution more than 30 years ago, are at a crucial point. In recent months, demonstrations have evolved from protests against the handling of the election to denunciations of the Islamic regime and its Supreme Leader Ayatollah Ali Khamenei.
Government-controlled media played down the news of Ayatollah Montazeri's death. Supreme Leader Khamenei offered his condolences, calling him "a well-versed jurist and a prominent master."
Ayatollah Montazeri, frail in recent years, was once in line to succeed Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic, as Supreme Leader. But he and Mr. Khomeini fell out in the late 1980s.
Ayatollah Montazeri accused Ayatollah Khamenei of creating a dictatorship in the name of Islam. Ayatollah Montazeri was placed under house arrest from 1997 to 2003. In time, he gained a large spiritual following because of his advocacy of reform inside the Islamic Republic and his calls for more democracy, The Wall Street Journal reports.