TEHRAN (AFP) - Iran police clashed with mourners at a memorial service in Isfahan on Wednesday for dissident cleric Grand Ayatollah Hossein Ali Montazeri, arresting more than 50 and beating women and children, reports said. Hundreds of police and security force members early morning surrounded the Seyed mosque in Isfahan where the service was to be held and prevented mourners from entering, sparking fierce clashes, opposition websites said.

The mourners were shouting slogans in support of Iran's opposition Green Movement and police fired tear gas to disperse them, website Rahesabz.net. said.

"Security forces are beating people including women and children with batons, chains and stones," it said, adding that "so far several have been arrested and many were injured."

Parlemannews.ir, the website of Iran's reformist minority faction in parliament, said that "over 50 people, including four reporters, were arrested in clashes."

The latest crackdown on the opposition comes a day after its major leader Mir Hossein Mousavi was sacked from his post as president of the Academy of Art, which the architect and painter had headed for 10 years.

Montazeri, a fierce critic of the clerical regime he helped create and a vocal backer of the opposition, died aged 87 on Saturday.

His funeral in the holy city of Qom on Monday saw hundreds of thousands of mourners pour onto the streets, effectively turning the ceremony into a massive anti-government protest which ended in clashes between police and mourners.

Wednesday's memorial service in Isfahan, where Montazeri had many followers, was to be led by prominent reformist cleric Ayatollah Jalaledin Taheri.

Another opposition website, Kaleme.org, said that an unnamed governmental body had ordered the memorial cancelled late Tuesday night and that the mosque doors had been closed and guarded by security forces.

Rahesabz said security forces had also surrounded the house of Ayatollah Taheri in Isfahan.

Montazeri came out in bold support of the opposition when it rejected the re-election of President Mahmoud Ahmadinejad in June and issued blistering statements condemning violence against demonstrators and branding the government "illegitimate."

Once tipped to succeed the founder of the 1979 Islamic revolution, Ayatollah Ruhollah Khomeini, he had long been critical of the concentration of power in the hands of the supreme leader and called for changes to the constitution to limit his authority.

Since his death, another prominent opposition supporter, Grand Ayatollah Yusuf Sanei, has faced pressure from hardliners, according to reformist website Norooznews.ir.

It said that on Monday night around 1,000 members of Iran's Basij Islamic militia attacked Sanei's offices in Qom, breaking windows and beating up his staff.

The attack follows speculation that Montazeri's followers could adopt Sanei as their new "source of emulation." Both clerics were disfavoured by hardliners.

A group of seminarians in Qom have called on senior clerics to officially declare Sanei incompetent to be a source of emulation, the official IRNA news agency said Wednesday.

"The Green Movement with Mousavi and (opposition leader Mehdi) Karroubi and Sanei's direct support ... explicitly insulted" Khamenei, the seminarians said in a statement.

Many hardliners have also called for Mousavi's arrest.

Fars news agency reported on Tuesday that Mousavi had been sacked from his position as president of the Academy of Art.

"Members of the Supreme Council of Cultural Revolution dismissed Mir Hossein Mousavi as head of the Academy of Art," council member Mohammad Mohammadian told the news agency. "Ali Moalem Damghani replaced him."

Mousavi, a former prime minister, had headed the Academy of Art since its establishment in 1999.

He still holds posts on a top cultural body and an arbitration body, whose members are appointed by the supreme leader.

Mousavi ran for president in June 12 elections which he lost to Ahmadinejad amid claims that the election was rigged, triggering sporadic protests since then.