An Iraqi security forces member stands looking at smoke billowing from the Ajeel oil field located 35km (22 miles) northeast of Tikrit on March 11, 2015. (AFP photo)
Iraqi forces on Saturday plotted ways of flushing out die-hard jihadists from central Tikrit, which one commander predicted would be liberated within three days.
Fighters from the Islamic State group are massively outnumbered and completely boxed in but they are protected by the thousands of bombs they planted across the city.
The broad alliance of fighting forces battling IS in the region is keen to minimise casualties on their way to what would be their biggest victory yet against the jihadists.
Karim al-Nuri, a top leader from the Badr militia and the spokesman of the volunteer Popular Mobilisation units, said it would take no more than "72 hours" to liberate Tikrit.
The last IS fighters holed up in the city centre were "surrounded from all sides", Nuri said. Speaking to AFP from the outskirts of Tikrit, near the village of Awja, he said "their number is now 60 to 70".
A lieutenant colonel in the Iraqi army's elite counter-terrorism service had a slightly higher estimate and a more conservative assessment of the battle's evolution.
"Battles in cities are difficult for all armies," he said. AFP reporters in a northern neighbourhood of Tikrit saw dozens of craters on a single street, caused by the explosion of bombs concealed underneath.
There was no evidence of intense fighting Saturday, after another day that saw Iraqi forces strike IS from above -- with artillery, jets and gunships -- but make little headway on the ground.
Army troops, police units, Popular Mobilisation units, Shiite militia groups as well as Sunni fighters eager to retake their own city launched a huge assault nearly two weeks ago.
They first cleared outlying areas in Salaheddin province, of which Tikrit is the capital, and broke the city's defences on Wednesday.
Tikrit is the hometown of former president Saddam Hussein, the remnants of whose Baath party collaborated with IS militants when they swept across Iraq's Sunni heartland nine months ago.
Baghdad has tried and failed several times to take back Tikrit but the ongoing operation is on a different scale, with up to 30,000 men initially involved.
Military coordination was improved, the cooperation of some Sunni tribesmen was secured and Iran is said to have played a key role in the operation's planning and execution.
Shrinking or expanding?IS has countered every military loss lately by ramping up its propaganda war with ever more shocking acts, including a video of a boy apparently executing a prisoner, and the destruction of priceless archaeological heritage sites.
It has also tried to project the image of an organisation that is still expanding, despite the fact its footprint in Iraq -- the home country of IS supremo and self-proclaimed "caliph" Abu Bakr al-Baghdadi -- has been shrinking steadily for months.
On Thursday, IS spokesman Abu Mohammed al-Adnani announced that a pledge of allegiance by the Boko Haram group had been accepted.
The Nigerian jihadist organisation has been suffering military setbacks of its own in recent weeks and the announcement came as no surprise.
"For both groups, the new linkage provides a much-needed propaganda victory at just the right moment," said the Soufan Group intelligence consultancy. "At this stage, the Islamic State will take any victory it can get," it said.
The outcome of the battle of Tikrit, seen by commanders as a key stepping stone on the way to reconquering IS' northern hub of Mosul, seems in little doubt but there is more at stake for the government than just territorial gain.
The vast operation is seen as test of Baghdad's ability to instill discipline in the array of fighting forces involved in the war effort against IS.
Shiite militias have been accused of serious crimes and abuses in reconquered areas, including of carrying out deadly revenge attacks against Sunnis.
In a report released late Friday, Human Rights Watch said government and allied forces had also "engaged in deliberate destruction of civilian property" after retaking the Turkmen town of Amerli in September.