ERBIL, Iraq (Reuters) - The battle to retake Mosul from Islamic State has become "very hard" in recent weeks but the pace will quicken once Iraqi forces manage to push in from the north and south of the city, a spokesman for the U.S.-led coalition said on Tuesday.
Iraqi government forces quickly recaptured outlying towns and villages when the Mosul campaign began last month, but have become bogged down in fierce street fighting since entering the city's eastern neighborhoods.
"Right now it's very hard," U.S. Air Force Colonel John Dorrian, a Baghdad-based spokesman for the coalition supporting Iraqi forces, told Reuters by telephone.
"ISIL (Islamic State) has been in the city for two years with a lot of time to build very elaborate defenses and to hoard weapons and resources that are now being used to complicate the advance," he said. Dorrian was referring to the jihadists' use of suicide car bombs and civilian human shields.
Iraq's elite Counter Terrorism Service (CTS) is making incremental advances in east Mosul in the face of the militants' use of suicide bombers and snipers to defend their Iraqi bastion.
Forces stationed to the north and south have meanwhile struggled to advance into the inner city itself. When those advances take place, progress will speed up, Dorrian said.
"As these additional forces converge on the city, that's really going to diffuse the Daesh (IS) defenses," he said. "(They) will no longer be able to concentrate the level of attention that they have on the eastern (districts).
"Iraqi security forces will develop a higher degree of momentum and a ... faster pace and tempo in liberating the city," he added.
Around 100,000 Iraqi government troops, Kurdish security forces and mainly Shi'ite Muslim militiamen are pitted against some 5,000-6,000 Islamic State fighters. The assault began on Oct. 17, with air and ground support from the coalition.
The city's capture is seen as crucial towards dismantling the Sunni insurgents' self-styled caliphate in Iraq and Syria.
Reporting by John Davison; editing by Mark Heinrich