Iraq's most revered Shiite cleric has called for unity among the country's forces battling Islamic State after most of the Iran-backed Shiite militias pulled out of the offensive in the militant-held city of Tikrit in protest over US air strikes there.
Grand ayatollah Ali al-Sistani's appeal came a day after the militias, which had been instrumental in the operation to recapture Saddam Hussein's home town, announced their boycott of the Tikrit offensive.
The US got involved in the operation and started providing air strikes on Wednesday in support of the mission at the request of Iraq's government.
Al-Sistani said co-ordination between the military, Shiite militias and tribes is necessary for the success of the operation, according to his representative Ahmed al-Safi at the holy site of Karbala.
It is up to the "high command of (the Iraqi) armed forces to adopt the proper and right decision", al-Sistani said.
On the ground, the Iraqi troops pressed their push in Tikrit today as fighter planes pounded IS targets from above. Militants holed up in the centre of Tikrit fired mortars at the military, slowing its progress despite the new aerial campaign.
A senior military commander said roadside bombs and booby traps planted by IS militants demanded extreme caution.
Iraq's military suffered a humiliating defeat during IS's lightning offensive last year when it crumbled in the face of the onslaught in Iraq's second-largest city, Mosul.
Days after the fall of Mosul, al-Sistani called on volunteers to rush to the battlefields and reinforce the military, and many of the country's militias reported for duty. But with a range of different leaders and loyalties, many of them became difficult to control.
Yesterday, Iraqi troops launched what commanders described as the final phase of the Tikrit offensive - this one without the Shiite militias. During the day, the clashes intensified as Iraqi troops and special forces moved toward the city centre, Lieutenant General Abdul-Wahab al-Saadi said.
The militias' pullout has prompted mixed reactions in Iraq. While several have been accused by human rights groups of atrocities against Sunni civilians, many in Iraq view them as the most capable fighting force in the country.
The militias also receive significant backing from Iran, one of Iraq's biggest allies, which raised the prospect of coalition interests uncomfortably overlapping with those of Iran.
At least two-thirds of the ground forces fighting in Tikrit were linked to Iraq's Popular Mobilisation Forces, the official government-backed body made up of different militias. The remaining fighters include the military and Iraq's Sunni tribes, the latter of which the US has cited as a crucial component to fighting the Sunni militant group.