The lawyer for Ramin Hossein Panahi was arrested on orders from the Revolutionary Court of Sanandaj on Saturday, the Kurdistan Human Rights Network has reported.
Niyaz was arrested at the court "while enquiring about the dossier of his client," according to KHRN.
Niyaz is also the lawyers for the Shin Abad burn victim school girls, and political prisoners Osman Mustafa Poour and Hedayat Abdollah Poour, a Kurdish prisoner on death row in Urmia.
"So far there is no information available on either the arresting authority or his whereabouts," added KHRN.
The family of Panahi believes his execution is imminent. They have also said he suffers from kidney disease.
Human rights agency Hengaw reported that authorities in Sanandaj prison plan to move Panahi from Sanandaj prison in Kurdistan province to Rajai Shahr prison in Karaj, near Tehran.
The prison is well known for the use of torture, rape, and murder. It is considered one of the worst jails in Iran.
Authorities are moving Panahi ahead of his execution in a bid to stem public outcry, according to Hengaw. His case has attracted international attention with UN experts and Amnesty International condemning his death sentence.
Panahi was arrested on June 22, 2017 in Sanandaj, and charged with being a member of the Kurdish opposition party Komala. The court stated that Panahi had received military training and was carrying a gun and a grenade at the time of his arrest.
Niyaz maintains Panahi was unarmed when he was arrested, while Iranian courts stated he had received military training and was carrying a gun and a grenade at the time of his arrest.
Iran carries out the second-most capital punishment executions per year in the world.
