The US-led coalition fighting Islamic State has said it was involved in an airstrike in west Mosul last week which is claimed to have caused hundreds of civilian casualties.
US Central Command said in a statement that "an initial review of strike data from March 16-23 indicates that, at the request of the Iraqi Security Forces, the Coalition struck ISIS fighters and equipment, March 17, in West Mosul at the location corresponding to allegations of civilian casualties".
Dozens of civilians have been killed by airstrikes in west Mosul in recent days, according to Iraqi officials.
The governor of Nineveh province, of which Mosul is the capital, Nawfal Hammadi, said coalition strikes in the Mosul al Jadida area had killed "more than 130 civilians".
While the head of the Nineveh provincial council, Bashar al-Kiki, told the AFP news agency: "There are dozens of bodies still under the rubble.
"Efforts to remove the bodies are ongoing."
It is impossible to independently confirm the number of dead, but there have been claims that up to 170 people died in the single airstrike on 17 March.
An Iraqi brigadier general told AFP that at least 27 residential buildings had been badly damaged when the attack was called in to deal with a number of Islamic State snipers.
Sky's Special Correspondent, Alex Crawford, has reported that "trapped civilians" in west Mosul have "built bunkers in their homes" as the "final battle for the Iraqi city gets under way".
She added that while some have fled, "hundreds of thousands of others remain pinned down".
In its statement, US Central Command said it had a goal of "zero civilian casualties".
It added that "CJTF-OIR (Combined Joint Task Force - Operation Inherent Resolve) takes all allegations of civilian casualties seriously and a formal Civilian Casualty Credibility Assessment has been opened to determine the facts surrounding this strike and the validity of the allegation of civilian casualties".
But it added that the coalition would not stop supporting its Iraqi partners "because of ISIS's inhuman tactics terrorising civilians, using human shields, and fighting from protected sites such as schools, hospitals, religious sites and civilian neighborhoods".
Governor Hammadi also accused IS of putting Mosul residents in harm's way.
"The Daesh terrorist organisation is seeking to stop the advance of the Iraqi forces in Mosul at any cost, and it is gathering civilians... and using them as human shields," he said.
The United Nations called for all sides to protect civilians during the battle.
"We are stunned by this terrible loss of life and wish to express our deepest condolences to the many families who have reportedly been impacted by this tragedy," Lise Grande, the UN's humanitarian coordinator for Iraq, said.
"Nothing in this conflict is more important than protecting civilians."