The wife of one of Iran's opposition leaders accused the nation's supreme leader Sunday of allowing violence and abuses to crush opponents, including the alleged beating of her son during last week's protests.

Fatameh Karroubi claimed her son Ali was savagely attacked inside a mosque by hard-line militiamen amid a massive security crackdown during events Thursday marking the 31st anniversary of the Islamic Revolution.

"They beat him up and insulted him along with other people arrested. This occurred in a house of God," she wrote in an open letter to Supreme Leader Ayatollah Ali Khamenei appearing on prominent pro-reform Web sites Rahesabz and Sahamnews.

The Web sites also posted photos purportedly showing bruises across Ali Karroubi's back.

She said the country's rulers have resorted to "violence and cruelty" in attempts to wipe out dissent.

The letter reflects the anger and dismay of many opposition groups after authorities unleashed a massive security crackdown to prevent disruptions of state-backed celebrations of the 1979 Islamic Revolution. There are now questions whether the opposition can rebound with more large-scale street demonstrations.

Ali Karroubi was hauled away during an attack on the motorcade of his father Mahdi Karroubi, who was an opponent of President Mahmoud Ahmadinejad in last June's disputed elections. The elder Karroubi was not injured, but he abandoned plans to attend an opposition gathering.

Ali's mother claimed that her son was taken from the mosque to a security base, where he received further beatings before he was released. She wrote that one agent told Ali that "his family would receive his corpse" if he was allowed to continue the punishment for another day.

She begged Khamenei to reverse the country's direction "before more people die." Khamenei, however, has strongly backed Ahmadinejad and the nation's powerful Revolutionary Guard, which has led the assault on the opposition.

"Unfortunately these days we don't have a proper justice system or a parliament who can truly defend people and their rights," she wrote. "So I'm asking you to help the people."

In Tehran, Iranian authorities detained five more members of the Baha'i minority, a hardline newspaper reported Sunday.

The daily Javan newspaper, which has ties to the elite Revolutionary Guards, reported that the five included Niki Khanjani, who is the daughter of Jamaloddin Khanjani, one of seven Baha'i leaders jailed since 2008 on charges of harming national security.

The report did not specify the current charges, but said many Baha'is have escaped to neighboring countries and the remote border areas of Iran after allegedly fomenting postelection unrest.

Opposition members have poured into the streets on several occasions since June to protest the result of the presidential election, which they maintain were tarnished by fraud.

Iranian authorities have repeatedly accused members of the Baha'i minority of being involved in the turmoil.

In January, the Tehran prosecutor said several followers of the Baha'i faith were detained in December protests for "organizing the riots and sending pictures of the protest abroad."

The minority has also been pursued for its religion, which was banned in 1979 after the Islamic revolution.

The Baha'i faith was founded in the 1860s by Baha'u'llah, a Persian nobleman considered a prophet by his followers. Islam considers Muhammad the last of the prophets and so conservatives reject the Baha'i faith.

Previously there had been reports that as many as 48 Baha'is were imprisoned in Iran solely on the basis of their religious beliefs.