BAGHDAD - Iraqi forces and mainly Shi'ite militiamen battling to wrest full control of the city of Tikrit from Islamic State militants paused their offensive for a second day on Saturday as they awaited reinforcements, a military source said.
More than 20,000 troops and Iranian-backed Shi'ite fighters entered Tikrit on Wednesday, having retaken areas to the north and south in Iraq's biggest offensive against the militants yet.
Islamic State fighters still hold about half the city and have booby-trapped buildings and laid improvised explosive devices and roadside bombs, the source in the local military command centre told Reuters.
More "well-trained forces" were needed for the street-by-street battles that recapturing the city would require, the source said, speaking by phone from Tikrit. He did not give a timeline for their arrival.
Victory for Iraq's Shi'ite-led government in Tikrit against the Sunni insurgents could provide a major boost to its forces as a broader confrontation with Islamic State looms in Mosul, the largest city in the north.
"We do not need a large number, just one or two thousand. We need professional personnel and soldiers," the source told Reuters.
Military commanders had "reached a decision to halt the operation until a suitable, carefully set plan is in place" to break into central Tikrit, the source said.
Islamic State overran Iraq's weakened army last year, seizing large amounts of territory where they have declared a caliphate and imposed brutal rule.
In Tikrit, which lies about 160 km (100 miles) north of Baghdad, the extremist group still controls central districts and a complex of palaces built by Saddam Hussein, the executed former Iraqi leader.
Iraqi security expert Hisham al-Hashemi doubted the city could be retaken with ground forces only, saying airpower was required to clear the many buildings which the IS fighters had rigged with explosives.
As the army and Shi'ite militias, who are known as Hashid Shaabi (Popular Mobilisation), recaptured IS-held towns near Tikrit, a small number of residents who had fled the militants' advance began to return home. Nearly two million Iraqis were displaced last year and officials have said that securing their return is a priority.
On Friday, some 200 families went home to the town of al-Alam with a security personnel escort from the government-held town of Dhuluiya, police sources there said.