Iranian authorities have arrested a niece of Supreme Leader Ayatollah Ali Khamenei after she recorded a video describing the authorities led by her uncle as a "murderous and child-killing regime", AFP reported on Sunday.

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.

Her brother, Mahmoud Moradkhani, wrote on Twitter that she was arrested on Wednesday after going to the office of the prosecutor following a summons.

On Saturday, her brother posted a video on YouTube, with the link shared on Twitter, in which the niece is seen condemning the "clear and obvious oppression" Iranians have been subjected to, and criticizing the international community's inaction.

"Free people, be with us! Tell your governments to stop supporting this murderous and child-killing regime," she said in the video, adding, "This regime is not loyal to any of its religious principles and does not know any law or rule except force and maintaining its power in any way possible."

She also complained that the sanctions imposed against the regime over its crackdown were "laughable" and said Iranians had been left "alone" in their fight for freedom.

Iran has seen two months of protests sparked by the death of 22-year-old Mahsa Amini on September 16, after she was arrested for an alleged breach of the country's strict dress rules for women based on Islamic sharia law.

As of Thursday, at least 426 people have been killed in the crackdown since Amini's death.

UN rights experts say thousands of peaceful protesters have also been arrested, including many women, children and journalists, and at least six people have so far been handed death sentences over the demonstrations.

Khamenei has claimed that the protests inside the country are the work of Israel and the United States.

"This rioting was planned," he said last month. "These riots and insecurities were designed by America and the Zionist regime, and their employees."

On Saturday, the Iranian Supreme Leader praised Iran’s Basij paramilitary force for its role in the deadly crackdown on anti-regime protesters, saying that the protesters are “rioters” and “thugs”.