Shia cleric Muqtada al-Sadr’s cabinet is not exclusive to clerics and Muslims, said the outspoken leader's chief public relations officer Shaikh Hasan al-Zirqawi on Sunday.
But the rival cabinet must be under Muslim religious supervision, said al-Zirqawi.
In his last Friday sermon in the southern town of Kufa, al-Sadr announced the formation of a rival cabinet to that installed by the US-appointed Governing Council.
“I have decided and I have formed a government made up of several ministries, including ministries of justice, finance, information, interior, foreign affairs, (religious) endowments and the promotion of virtue and prevention of vice,” he said.
Al-Sadr called on those who supported his cabinet to demonstrate peacefully.
Al-Sadr heads the Mahdi army militia, made up of thousands of supporters.
He was ignored by the US occupying administration in the formation of a Governing Council, on which he is not represented.
The Council was created along sectarian and ethnic lines.
Meanwhile, a grenade carried by an Iraqi apparently detonated early, wounding a policeman and civilian on Sunday in an attempted attack against a police checkpoint in the northern Iraqi city of Kirkuk.
Shia Muslims increasingly opposing
The attacker, identified as Ghalab Nasr al-Din, 32, died when the grenade he evidently planned to hurl at the police post, blew up in his hands, according to local police chief Lieutenant Colonel Adal Zein al-Din.
The police chief said the attack was the latest in a series targeting local police and aimed at destabilising Kirkuk.
An Iraqi policeman also died overnight of wounds sustained in an attack on a police checkpoint in Kirkuk, said police.
Officer Muhammad Ghafur, 45, was wounded last Wednesday when attackers fired a rocket-propelled grenade at the checkpoint, killing another policeman.
Iraqi police are increasingly coming under attack, including last week’s deadly strike against a Baghdad police station which left about eight people dead.