PMF fighters fire at ISIS militants near Tikrit, May 25, 2015

BAGHDAD — An Iraqi Shi’a paramilitary group said it will join government forces preparing to fight ISIS for Mosul despite objections of politicians who fear this could instigate sectarian bloodshed in the mostly Sunni Muslim city.

A much-touted government offensive to retake Iraq’s largest northern city two years after its seizure by the extremist insurgents has made a faltering start, casting doubt on the army’s ability to do so without more ground support.

The campaign will require the participation of the Popular Mobilization Forces (PMF), a coalition of mostly Shi’a Muslim militias, said a spokesman for Asaib Ahl al-Haq, one of its most powerful factions.

“We think the battle to liberate Mosul will be huge, complex; it will be about guerrilla warfare in built-up areas, which only PMF fighters are good at …, as forces may be fighting house to house, room to room,” the spokesman, Jawad al-Talabawi, said in an interview on Wednesday in Baghdad.

In an opinion column published in the New York Times on March 27, Iraqi Parliament Speaker Salim al-Jabouri made a plea to keep the PMF out of Mosul, the capital of Nineveh province.

Jabouri, the most senior Sunni official in the country, said the PMF had destroyed Sunni houses and mosques, carried out reprisal killings in villages recaptured from ISIS and barred people from returning to their homes.

To avoid atrocities, Jabouri said, the Mosul campaign should replicate the recent recapture from ISIS of Ramadi, capital of mainly Sunni Anbar province, by Iraqi army troops backed by Sunni tribal fighters and U.S.-led air strikes.

Until Ramadi’s recapture in December, it was the PMF, assisted by Iranian military advisers, that spearheaded operations to recover territory from ISIS.