Ayatollah Ali Khamenei
Ayatollah Ali KhameneiReuters

The sister of Iran's Supreme Leader, Ayatollah Ali Khamenei, has slammed her brother’s "despotic" rule and thrown her support behind protests ignited by Mahsa Amini's death, in a letter published Wednesday by her son and quoted by AFP.

"I oppose my brother's actions," Khamenei's sister Badri Hosseini Khamenei, who is believed to be in Iran, said in a letter published online by her France-based son Mahmoud Moradkhani.

"I express my sympathy with all mothers mourning the crimes of the Islamic republic regime," from the time of its founder Ayatollah Ruhollah Khomeini "to the current era of the despotic caliphate of Ali Khamenei", she wrote.

"My concern has always been and will always be the people, especially the women of Iran," she added.

She accused the regime of bringing "nothing but suffering and oppression to Iran and Iranians" since it was established following the 1979 Islamic revolution that toppled the shah.

"The people of Iran deserve freedom and prosperity, and their uprising is legitimate and necessary to achieve their rights. I hope to see the victory of the people and the overthrow of this tyranny ruling Iran soon," she said.

"My brother does not listen to the voice of the people of Iran and wrongly considers the voice of his mercenaries and money-grabbers to be the voice of the Iranian people. He rightly deserves the disrespectful and impudent words he uses to describe the oppressed but brave people of Iran," she wrote.

Protests have gripped Iran following the September 16 death of 22-year-old Mahsa Amini after she was arrested by the morality police.

Hundreds of protesters have been killed in more than two months of nationwide unrest, including dozens of minors. In addition, at least six people have so far been handed death sentences over the demonstrations.

Iranian leaders, including Khamenei, have claimed that the protests inside the country are the work of Israel and the United States.

His sister’s remarks come a week and a half after Iranian authorities arrested a niece of Khamenei after she recorded a video describing the authorities led by her uncle as a "murderous and child-killing regime".

The niece, Farideh Moradkhani, comes from a branch of the family that has a record of opposition to Iran's clerical leadership and has herself been jailed previously in the country.