BAGHDAD (Reuters) - At least two Sunni Muslim mosques have been attacked in Iraq and two people killed in apparent retaliation for the execution of a senior Shi’ite cleric in Sunni-ruled Saudi Arabia, officials and police said on Monday.

Supporters of Shi'ite cleric Moqtada al-Sadr protest against the execution of Shi'ite Muslim cleric Nimr al-Nimr in Saudi Arabia, during a demonstration in Baghdad January 4, 2016. REUTERS/Thaier Al-Sudani

Iraqi Shi’ites protesting the Jan. 2 execution of Saudi Shi’ite cleric Nimr al-Nimr separately marched in Baghdad and southern cities, while a powerful Iranian-backed Shi’ite militia group pressured the government to sever ties with Riyadh.

Iraq’s Interior Ministry confirmed the attacks on Sunni mosques late Sunday in Hilla, around 100 km (60 miles) south of Baghdad. Prime Minister Haider al-Abadi blamed them on “Daesh (Islamic State) and those who are similar to them,” without further explanation.

He ordered provincial authorities “to chase the criminal gangs” who attacked the mosques.

Iraq has faced sectarian bloodletting for years, mainly between minority Sunnis and a Shi’ite majority empowered after the U.S.-led invasion in 2003. The battle against Sunni Islamic State militants who control large swathes of the north and west has only exacerbated those tensions.

The spark for Sunday’s attacks appears to have been Nimr’s execution a day earlier, which triggered angry reactions in Shi’ite-led Iraq and Iran.

Saudi Arabia cut ties with regional rival Iran on Sunday after protesters attacked the kingdom’s embassy in Tehran. Bahrain, the Shi’ite-majority Gulf state ruled by a Sunni family, and Sudan followed suit on Monday.

The attack on a mosque in central Hilla destroyed its dome and several walls, according to a Reuters TV cameraman who visited the site. Provincial council member Falah al-Khafaji and a police source said a guard in the building was killed.

“We saw smoke rising from the dome of the mosque. We found all the walls destroyed and the furniture inside in shambles,” said resident Uday Hassan Ali.

Another mosque in Hilla’s northern outskirts was also attacked, and a Sunni cleric was killed in a separate incident in Iskandariya, about 40 km (25 miles) south of Baghdad, Khafaji and the police source said.

“We have leads and security measures will be taken near mosques,” said Khafaji, pledging to rebuild the buildings.

PROTESTS

Prominent religious and political leaders in Iraq have called on the government to cut ties with Saudi Arabia, which reopened its Baghdad embassy last week after closing it in 1990 following the Iraqi invasion of Kuwait.

While Abadi and Iraq’s foreign ministry have condemned Nimr’s execution, they have given no indication of a more severe response.

Asaib Ahl al-Haq, a powerful Shi’ite militia backed by Iran, on Monday warned the government against inaction.

“We demand the government expel the Saudi ambassador... (otherwise) the government will be responsible for the popular backlash,” it said in an online statement calling for the implementation of death sentences issued against Saudi “terrorists”.

The group said it was speaking on behalf of the “Islamic resistance”, a term commonly used for Iranian-backed Shi’ite militias, but did not specify which groups it represented.

Earlier thousands of protesters marched in Baghdad and Shi’ite cities in southern Iraq, heeding calls by prominent Shi’ite cleric Moqtada al-Sadr to protest against Nimr’s execution.

In Baghdad, demonstrators carrying portraits of Nimr, wearing a gray beard and a white turban, rallied outside the heavily fortified Green Zone housing government departments and diplomatic representations, including the newly reopened Saudi embassy.

Police guarding the zone pushed back a group of protesters trying to cross a line of barbed wire as they chanted “damned, damned be Al Saud,” referring to the Saudi ruling family.

Similar protests were held in Basra, southern Iraq’s biggest city, and in the Shi’ite holy cities of Najaf and Kerbala.