Huge crowds of Iranians turned out for the funeral of leading dissident cleric Grand Ayatollah Hossein Ali Montazeri in the holy Shia city of Qom today, and some chanted anti-government slogans, websites reported.
Mr Montazeri, who died late on Saturday aged 87, was viewed as the spiritual patron of a pro-reform opposition movement that blossomed after a disputed presidential election in June and has remained resilient despite repeated efforts to suppress it.
Violence flared when security forces around Mr Montazeri's house clashed with stone-throwing protesters, the reformist website Norooz said. There was no immediate official comment.
The moderate Parlemannews website cited "information received" of shots fired in the air near Qom's main shrine and also of the use of tear gas, without giving details.
The reports could not be verified independently since foreign media were banned from reporting directly on protests and were told not to travel to Qom for Montazeri's funeral. But pictures obtained by Reuters showed scuffles apparently between government and opposition supporters.
The reformist website Jaras said hundreds of thousands of people joined a procession for Montazeri, a pillar of Iran's 1979 Islamic revolution. He later became a fierce critic of its hardline leadership and a staunch defender of reformists.
"Innocent Montazeri, your path will be continued even if the dictator should rain bullets on our heads," the crowd chanted. The conservative Ayande website estimated the number of people attending the funeral ceremony at tens of thousands.
Iran's internal unrest, highlighted by Mr Montazeri's arguments that the leadership had lost its legitimacy, has complicated the dispute over the Iranian nuclear programme, which the West believes may have military ends, not just civilian purposes.
Opposition leaders Mirhossein Mousavi and Mehdi Karoubi were photographed paying their condolences at Montazeri's house. Reformist websites said security forces arrested some opposition supporters trying to reach Qom and turned others away.
The cleric's death occurred in the tense run-up to Ashura, a politically laden Shia religious commemoration that offers the opposition another opportunity to show its strength.
Ashura, a key occasion in the Islamic Republic's calendar, will coincide with the seventh day of mourning for Montazeri, making it harder for authorities to keep people off the streets.
Riot police were out in force in Qom, 125km south of Tehran, for the funeral of the senior Shia cleric who had been a thorn in the establishment's side. Pro-government Basij militiamen shouted: "Shame on you hypocrites, leave the city of Qom," said the Ayande website. Mourners chanted back: "What happened to the oil money? It went to the Basijis."
Mr Montazeri was named in the 1980s to succeed revolutionary leader Ayatollah Ruhollah Khomeini, but was shunted aside after he criticised the mass execution of political prisoners. Supreme Leader Ayatollah Ali Khamenei, who succeeded Mr Khomeini after he died in 1989, expressed condolences, but he asked God to forgive Montazeri over a "difficult and critical test" that he faced towards the end of Khomeini's life - making clear that he believed his old rival had failed the test.
Iranian newspapers published no pictures of Mr Montazeri on their front pages, in line with what reformist websites said were orders from the Ministry of Culture and Islamic Guidance.
Reuters