Nayef Kurdistani "was arrested by the Kurdistan region's security forces" and is being held in custody in the Kurdish capital Arbil, the autonomous region's interior ministry said in a statement.

He stands accused of making "reprehensible remarks", after a post on his Twitter account in which the author contended that the "Persian" religious authority, among others, is not descended from the Prophet Mohammed, even if they "wear black turbans".

A black turban, when worn by Shiite clerics -- notably Sistani -- signifies direct lineage from the Prophet Mohammed.

The post has since been deleted and Kurdistani denies being the author, claiming his account had been hijacked.

Article 372 of Iraq's constitution stipulates a prison term of up to three years for insulting "a symbol or person which / who is an object of sanctification, worship or reverence".

Sistani, 91, was born in Iran and lives in the Iraqi Shiite holy city of Najaf. Shiites form a majority in Iraq.

Kurdistani ran as a parliamentary candidate for the Kurdistan Democratic Party in Iraq's 2018 elections, but failed to win a seat.

A crowd set the party's Baghdad headquarters ablaze overnight, without causing casualties.

The KDP says Kurdistani is no longer a party member.