Iraqi Shia leader calls followers to 'holy war'

Spiritual leader for Iraq's Shia Muslims Ayatollah Ali al-Sistani called his followers to a "holy war" against "terrorism" during Friday prayers.

Sistani issued a religious ruling, known as a fatwa, for Shia Muslims to take up arms to "defend" Iraq.

Sistani was referring to the recent splintering of government control over the country after series of operations by militant group Islamic State of Iraq and the Levant,or ISIL, which began Tuesday.

"Citizens who are able to bear arms and fight terrorists, defending their country and their people and their holy places, should volunteer and join security forces to achieve this holy purpose," reads the fatwa. Those who "loses his life for defending the country of the enemies of Shia, will be a martyr."

Northern and western Iraq have been left in chaos since ISIL and affiliated groups seized the northern city of Mosul, where Iraqi troops have withdrawn from their posts.

On Wednesday, they seized the city of Tikrit -- 140 kilometers northwest of Baghdad -- and several towns and regions have fallen under their control as they threaten to move south towards Baghdad. The militant group has held control of western Anbar province since January.

Sistani's fatwa comes as reports say that ISIL are advancing towards the Iraqi capital.

Karbala city, 100 kilometers southwest of Baghdad, is one of the holiest cities for Shia muslims.

ISIL was established shortly after the U.S.-led invasion of Iraq in 2003 and was most recognizably known as al-Qaeda in Iraq, under the leadership of Jordanian militant Abu Musab al-Zarqawi.

Al-Qaeda leader Ayman al-Zawahiri cut ties with ISIL in February 2014 after a dispute with another militant group, Jabhat al-Nusra.

Iraq has seen a marked increase in sectarian violence between Sunni and Shia Muslims in recent months, which the Iraqi government blames on ISIL.