Repairing Mosul's infrastructure will 'cost $1 billion'

Repairing Mosul's infrastructure after a US-backed Iraqi offensive to recapture the city from the Islamic State will cost more than $1 billion, a UN official said on Wednesday.

Iraq's security forces are in the final stages of the gruelling battle to retake second city Mosul, which they launched more than eight months ago.

Last week, they retook the area around the al-Nuri Mosque, which the IS militants had blown up just a few days earlier.

Nearly all parts of the city have incurred light or moderate damage in the military offensive, with some districts completely destroyed and requiring years to rebuild.

"In western Mosul what we're seeing is the worst damage of the entire conflict," Lise Grande, the United Nations' Humanitarian Coordinator for Iraq, told Reuters.

"In those neighbourhoods where the fighting has been the fiercest, we're looking at levels of damage incomparable to anything else that has happened in Iraq so far."

Repairing water, sewage and electricity infrastructure, together with reopening schools and hospitals, will cost more than double the initial estimates, she added.

While eastern Mosul could be stabilised in two months, it will take more than a year in the western part of the city, where at least six of the 44 districts were destroyed.

"What that shows is that the level of damage is far higher than we expected, and that's why the cost of stabilisation is far higher," Grande added.

The Mosul operation has taken a heavy toll on civilians, pushing more than 900,000 to flee their homes and leaving hundreds dead or wounded.

IS overran Mosul and swathes of other territory in 2014, but Iraqi forces backed by US-led air strikes have since recaptured most of those areas.