World

Iraq's top Shiite cleric urges unity in anti-IS fight after militias pulled out of Tikrit

  • Smoke rises from buildings in central Tikrit, Iraq, during clashes between Iraqi security forces and Islamic State group extremists in the city, 130 kilometers (80 miles) north of Baghdad, Iraq, Thursday, March 26, 2015. Iraqi troops started the final phase of an offensive to recapture Saddam Hussein's hometown of Tikrit on Thursday, a military official said, just hours after the United States launched airstrikes on the Islamic State held city. (AP Photo/Khalid Mohammed)

    Smoke rises from buildings in central Tikrit, Iraq, during clashes between Iraqi security forces and Islamic State group extremists in the city, 130 kilometers (80 miles) north of Baghdad, Iraq, Thursday, March 26, 2015. Iraqi troops started the final phase of an offensive to recapture Saddam Hussein's hometown of Tikrit on Thursday, a military official said, just hours after the United States launched airstrikes on the Islamic State held city. (AP Photo/Khalid Mohammed)  (The Associated Press)

  • Iraqi security forces launch a rocket against Islamic State extremist positions during clashes in Tikrit, 130 kilometers (80 miles) north of Baghdad, Iraq, Thursday, March 26, 2015. Iraqi troops started the final phase of an offensive to recapture Saddam Hussein's hometown of Tikrit on Thursday, a military official said, just hours after the United States launched airstrikes on the Islamic State held city. (AP Photo/Khalid Mohammed)

    Iraqi security forces launch a rocket against Islamic State extremist positions during clashes in Tikrit, 130 kilometers (80 miles) north of Baghdad, Iraq, Thursday, March 26, 2015. Iraqi troops started the final phase of an offensive to recapture Saddam Hussein's hometown of Tikrit on Thursday, a military official said, just hours after the United States launched airstrikes on the Islamic State held city. (AP Photo/Khalid Mohammed)  (The Associated Press)

  • Iraqi security forces prepare to attack Islamic State extremist positions in Tikrit, 130 kilometers (80 miles) north of Baghdad, Iraq, Thursday, March 26, 2015. Iraqi troops started the final phase of an offensive to recapture Saddam Hussein's hometown of Tikrit on Thursday, a military official said, just hours after the United States launched airstrikes on the Islamic State held city. (AP Photo/Khalid Mohammed)

    Iraqi security forces prepare to attack Islamic State extremist positions in Tikrit, 130 kilometers (80 miles) north of Baghdad, Iraq, Thursday, March 26, 2015. Iraqi troops started the final phase of an offensive to recapture Saddam Hussein's hometown of Tikrit on Thursday, a military official said, just hours after the United States launched airstrikes on the Islamic State held city. (AP Photo/Khalid Mohammed)  (The Associated Press)

Iraq's most revered Shiite cleric is calling for unity among the country's forces battling the Islamic State group after major, Iran-backed Shiite militias pulled out of the offensive in the militant-held city of Tikrit in protest over U.S. airstrikes there.

Grand Ayatollah Ali al-Sistani's spokesman, Ahmed al-Safi, says the top cleric's message for Friday prayers was that such splits among Iraqi forces will have a negative impact.

According to al-Safi, al-Sistani says coordination between the military, Shiite militias and tribes is necessary for the success of the operation to retake Saddam Hussein's hometown and defeat IS.

On Thursday, most of the Shiite militias announced their boycott of the Tikrit operation, after the U.S. got involved and started providing airstrikes in support of the mission at the request of Iraq's government.