Iraq’s most senior Shiite cleric has issued a call to arms after Sunni-led insurgents seized more towns, the BBC reported on Friday.

The call by a representative of Grand Ayatollah Ali al-Sistani came as the Islamists from the Islamic State in Iraq and the Levant (ISIS) widened their grip in the north and east, and threatened to march south, towards Baghdad.

In his sermon at Friday prayers in Karbala, Sheik Abdulmehdi al-Karbalai said, “Citizens who are able to bear arms and fight terrorists, defending their country and their people and their holy places, should volunteer and join the security forces to achieve this holy purpose.”

There are reports that thousands have already joined Shiite militias which could play a crucial role in the defense of Baghdad, according to the BBC.

Meanwhile Iraq’s Ministry of Communications has started blocking social media sites in the capital, according to the privately-owned Iraqi news agency Al-Mada.

The call by the Shiite cleric came a day after reports indicated that Iran has deployed Revolutionary Guards units to Iraq in order to fight the Islamists who have taken over cities there.

Iran is not a stranger to doing this, as it is already involved in Syria’s civil war, where it has provided President Bashar Al-Assad with military support during his fight against the rebels.

Iran, which is a majority Shiite Muslim country, shares a border with Iraq and has a direct line to Iraq’s Shiite Muslim Prime Minister, Nouri Maliki, noted the BBC, adding that the Iranians could direct their proxies, and even their own special forces units, at ISIS.

Officials in Tehran have denied, however, that their forces are actively operating inside Iraq, noted the report.

(Arutz Sheva’s North American Desk is keeping you updated until the start of Shabbat in New York. The time posted automatically on all Arutz Sheva articles, however, is Israeli time.)