BAGHDAD (Reuters) - Iraqi Shi’ite paramilitary groups who took part in the war against Islamic State militants should be incorporated into state security bodies, the nation’s top Shi’ite cleric said.

In a message delivered at the Friday sermon in the holy city of Kerbala through one of his representatives, Grand Ayatollah Ali al-Sistani said all weapons used in fighting the insurgents should be brought under the control of the Iraqi government.

Sistani’s position is in line with that of Prime Minister Haider al-Abadi, who wants to prevent commanders of the militias known as Popular Mobilisation Forces (PMF) from using power and clout they acquired during the war in elections due on May 12.

Sistani was the author of a landmark fatwa, or religious decree, which urged Iraqis to volunteer for the war on Islamic State after the government’s armed forces collapsed in 2014 and the militants swept towards the gates of Baghdad.

“The victory over Daesh doesn’t mean the end of the battle with terrorism,” Sistani’s representative Sheikh Abdulmehdi al-Karbalai said, mentioning the existence of “sleeper cells”.

“The security apparatus should be supported by the fighters who took part in the war on Daesh,” he added in the sermon broadcast on state TV, using an Arab acronym for Islamic State.

“It is necessary to absorb the fighters in the official and constitutional structures,” Sistani said in the sermon, adding that “the fatwa should not be used to achieve political aims”.

Abadi quickly reacted to Sistani’s sermon in a statement from his office “welcoming his call against using volunteers and fighters in political campaigning”.

Iraq’s Sunni and Kurdish politicians have called on Abadi, who declared victory over Islamic State last week, to disarm the PMF. They say the militias are responsible for widespread abuses including extra-judicial killings, kidnappings and displacing non-Shi’ite populations, and in effect report to Tehran, not the government in Baghdad.

The PMF says any abuses were isolated incidents and not systematic and that those who committed them have been punished.

Two of the most important Iranian-backed paramilitary leaders, Hadi al-Amiri and Qais al-Khazali, announced this week they were putting their militias under Abadi’s orders.

Their decision to formally separate their armed and political wings could pave the way for them to contest the elections, possibly as part of a broader alliance close to Iran.

Iran provided training and supplied weapons to the most powerful PMF groups including Amiri’s Badr Organisation and Khazali’s Asaib Ahl al-Haq.

The Iraqi parliament last year voted to establish the PMF as a separate military corps that reports to Abadi in his capacity as commander-in-chief of the armed forces.