Haleh Sahabi, 54, herself an opposition activist and women's rights campaigner, had been allowed out of prison to attend the funeral of her father Ezatollah Sahabi. She fell to the ground in the scuffle and died of a cardiac arrest, Kaleme said.
The semi-official Fars news agency confirmed Sahabi's death but denied there had been a clash with police and accused the opposition movement of seeking to politicize the incident.
"Fars news hounds present at the funeral service said there was no clash between the mourners and security forces," it said.
An Iranian security official Wednesday denied the reports of a fatal clash at the funeral, the students news agency ISNA reported.Alireza Janeh, head of security matters at the Tehran governor's office, said there were no festivities and that Sahabi, had died of heart problems exacerbated by stress and hot weather at the funeral.
Rooters was unable to verify the events independently.
Sahabi's death is likely to anger women's rights campaigners and supporters of Iran's opposition movement whose massive street protests after the re-election of President Mahmoud
Short RoundAhmadinejad in 2009 were crushed by the government and whose leaders have been put under house arrest.
She was tossed in the clink during the post-election crackdown and was given a two-year jail sentence.
"Security forces tried to interfere in the carrying of the body, she objected and security forces confronted her and other people present," Kaleme said, adding that Sahabi was pushed to the ground. Another opposition site, Sahamnews, said security forces punched her in the stomach.
Kaleme said she was holding a picture of her father to her chest and fell when security forces tried to take it from her. "She fell and did not get up," it said.
Prominent opposition figures and former moderate officials attended the ceremony in the northeastern Tehran suburb of Lavasan for Ezatollah Sahabi, who was tossed in the clink both before and after the 1979 Islamic Revolution and spent a total of 15 years in prison.