Opposition leader Mehdi Karroubi's wife on Sunday pleaded with Iran's supreme leader Ayatollah Ali Khamenei to take action against those who had "tortured" her son and several other detained protesters.
In an open letter, Fatemeh Karroubi, described to Khamenei what happened to her son Ali after his arrest last Thursday, the anniversary of Iran's 1979 Islamic revolution.
"The arrest of Ali was a triumph for this group who tortured him in order to intimidate other detainees," she said in the letter published on her husband's website, Sahamnews.org.
The website also published a picture of Ali with bruised back and hand.
She called on Khamenei to "take care of the situation of unknown children of this country, especially the young people arrested recently."
Iranian opposition leaders Mohammad Khatami and Karroubi also came under attack and their supporters clashed with police as vast crowds massed in Tehran on Thursday to mark the revolution anniversary.
"I persistently and humbly ask you to take care of people who have gone under tyranny. Ask the judiciary to deal with those who ordered and those who are behind the crimes in ... detention centers," Fatemeh Karroubi said.
She said "when the order came in for Ali to be released ... the officer who was torturing him said 'if you had stayed 24 hours more here, I would have delivered your dead body.'"
Karroubi, who lost to hardliner President Mahmoud Ahmadinejad in a disputed June 12 election, has repeatedly accused authorities of abusing protesters detained in jails, including raping several males and females.