Iranian opposition leaders have vowed to gather at a cemetery in the capital Tehran to mourn protesters killed in unrest after a disputed presidential election.
Mir Hossein Mousavi and Mehdi Karroubi, the two defeated reformist candidates who claimed the vote was rigged, said they would visit the graves of the protesters on Thursday, to mark 40 days since the deaths.
"The offices of Mehdi Karroubi and Mir Hossein Mousavi announce that the two will go to the graves of those dead in the recent incidents along with their families and pay their respects," a statement on Karroubi's website said.
Media reports said that the mother of Neda Agha-Soltan, a protester who was killed on June 20 and has since become a symbol of the opposition, would be among those visiting the cemetery.
Neda, a 26-year-old music student, was shot on June 20, as protesters clashed with riot police and members of the pro-government Basij militia in Tehran.
At least 20 people are believed to have been killed and several thousands arrested in the crack down following the re-election of Mahmoud Ahmadinejad, the Iranian president, in the contested vote on June 12.
Several people accused of rioting are to go on trial from Saturday on a range of charges including attacks on government and military offices, arson, vandalism and contacts with "enemies", including the People's Mujahideen, a banned opposition group.
"We have pictures showing them committing these crimes," Saeed Mortazavi, the Tehran prosecutor, said on Wednesday.
However, there was also an apparent acknowledgement of abuse by members of the security forces as they targeted protesters, political activists and journalists in the aftermath of the election.
"Some officers went to extremes in these incidents and they inflicted damage on people while chasing the rioters," Esmail Ahmadi Moghaddam, Iran's police chief was quoted as saying.
"Nothing should make our forces break the law."
The unrest following the presidential poll has also exposed the divisions between the conservatives and reformists in the country's ruling elite.
Rasool Montajebnia, Karroubi's deputy, has suggested that Mousavi, a former prime minister, Karroubi and Mohammad Khatami, a former president, form a joint council to advance the opposition movement.
"If they individually carry out actions, it cannot become a comprehensive movement and address people's demands," he was quoted as saying by Karroubi's Etemad Melli newspaper.
"There is no way but to establish a council of reform ... around the axis of Khatami, Karroubi and Mousavi."
Ahmadinejad is due to be sworn in as president next week, but his standing has been weakened after Ayatollah Ali Khamenei, Iran's supreme leader, ordered him to dismiss his choice for first vice-president.