The offensive to retake Tikrit appeared to have slowed down on 13 March, two days after Iraqi security forces and Shi'ite militia pushed into the late Saddam Hussein's home city in their biggest offensive yet against Islamic State (Isis).

IS still holds around half of Tikrit. Using guerrilla warfare tactics, the militants have turned the city into a labyrinth of home-made bombs and booby-trapped buildings, and are using snipers.

More than 20,000 Iraqi troops and Shi'ite militias are taking part in the offensive, which began 11 days ago, advancing from the east.

battle for Tikrit Isis
Smoke from a clash with Islamic State militants rises behind a sign saying 'Welcome to Tikrit'Thaier al-Sudani/Reuters
battle for Tikrit Isis
Shi'ite fighters known as Hashid Shaabi walk as smoke rises from a vehicle driven by an Islamic State suicide bomber on the southern edge of TikritThaier al-Sudani/Reuters
battle for Tikrit Isis
Smoke rises from an explosives-laden military vehicle driven by an Islamic State suicide bomber which exploded during an attack on the southern edge of TikritThaier al-Sudani/Reuters
battle for Tikrit Isis
Shi'ite fighters of the government-controlled Popular Mobilisation units stand at the site of a car bomb that targeted pro-government forces in a suburb west of TikritAhmad al-Rubaye/AFP
battle for Tikrit Isis
A member of the Popular Mobilisation unit, with 'Daesh' (an Arabic acronym for Islamic State) written on his boots takes part in a military operation in the village of Albu Ajil, near Tikrit,Ahmad al-Rubaye/AFP
battle for Tikrit Isis
Mourners carry the coffin of a Shi'ite fighter who was killed in clashes with Islamic State militants in Tikrit, during his funeral in NajafAlaa Al-Marjani/Reuters
battle for Tikrit Isis
Mourners react during the funeral of a Shi'ite fighter who was killed in clashes with Islamic State militants in Salahuddin province, during his funeral in NajafReuters
battle for Tikrit Isis
Iraqi medics treat wounded fighters at a field hospital as forces entered a northern neighbourhood of TikritAhmad al-Rubaye/AFP

A victory in Tikrit would give Iraqi forces momentum for the next stage of the campaign to retake Mosul, the largest city under IS control.

Any assault on Mosul is likely to be a far more complex undertaking. The northern city is larger, further away from core government-held territory and still densely populated, unlike Tikrit, most of whose residents fled long before the operation began.

IS spokesman Abu Mohammad al-Adnani said in a recording that its fighters remained "steadfast" and were growing in strength, dismissing its enemies claims of gains in Tikrit as "fake".

battle for Tikrit Isis
A fighter stands in front of a wall painted with the black flag commonly used by Islamic State militants, in al-AlamThaier al-Sudani/Reuters
battle for Tikrit Isis
Residents welcome a relative who is part of militias known as Hashid Shaabi, in the town of al-AlamThaier al-Sudani/Reuters
battle for Tikrit Isis
A woman holding a weapon and the Iraqi flag welcomes her relative who is part of militias known as Hashid Shaabi, in the town of al-AlamThaier al-Sudani/Reuters
battle for Tikrit Isis
A militia walks with his weapon in the town of al-AlamThaier al-Sudani/Reuters
battle for Tikrit Isis
Armoured vehicles driven by Iraqi security forces and militias known as Hashid Shaabipass smoke arising from a clash with Islamic State militants in the town of al-AlamThaier al-Sudani/Reuters
battle for Tikrit Isis
Shi'ite fighters and Iraqi security forces clash with Islamic State militants in the town of al-AlamThaier al-Sudani/Reuters
battle for Tikrit Isis
A member of Iraqi security forces runs with an Islamic State flag that was pulled down in the town of al-Alam, near TikritThaier al-Sudani/Reuters
battle for Tikrit Isis
A member of the tribal groups fighting along with the Iraqi government security forces takes a position behind sandbags during clashes with jihadists in the Hosh district of RamadiAzhar Shallal/AFP

IS is also on the back foot in the north, where Shi'ite militia and Kurdish forces known as peshmerga went on the offensive around the oil-rich city of Kirkuk.

The peshmerga have retaken territory and a number of villages to the south-west of Kirkuk. Kurdish commanders said they had faced relatively weak resistance but were being held up by home-made bombs the militants laid before retreating to their stronghold of Hawijah.

battle for Tikrit Isis
Iraqi Kurdish Peshmerga fighters stand next to an Islamic State sign at the entrance to the town of Hawija, south of Kirkuk after they reportedly re-took the area from IS jihadistsMarwan Ibrahim/AFP
battle for Tikrit Isis
A member of the Kurdish Peshmerga forces looks at a cloud of smoke rising from buildings in a village east of KirkukMarwan Ibrahim/AFP
battle for Tikrit Isis
Kurdish Peshmerga forces inspect a bridge that was destroyed by Islamic State militants on the outskirts of KirkukAko Rasheed/Reuters