US-backed Iraqi regular and paramilitary forces recaptured 15 villages from the so-called "Islamic State" (IS) on Sunday as part of an operation to take the west of Mosul.

"We launched our operation at 7:00 a.m. (0400 UTC)... We are heading towards the airport," said Abbas al-Juburi of the interior ministry's elite Rapid Response force. There were air strikes and artillery fire in support of the operation. More than half of the 9,000-plus coalition forces deployed in Iraq are American. Some were visible on the front line Sunday, according to AFP.

The forces reached Zakrutiya, a small village 5 kilometers (3 miles) south of the airport by the end of the day, the statements said.

IS fighters have put up fierce resistance from entrenched positions within the city they have occupied for the last two years. "Mosul would be a tough fight for any army in the world," the commander of the US-led coalition forces Lt. Gen. Stephen Townsend said in a statement, adding that the coalition has carried out more than 10,000 air strikes against IS in Iraq and trained and equipped more than 70,000 Iraqi forces.

US Defense Secretary Jim Mattis said "The coalition forces are in support of this operation and we will continue ... with the accelerated effort to destroy ISIS."

Humanitarian concerns

Charities have expressed concern for the fate of hundreds of thousands of civilians trapped inside the city. Many of them are believed to be children.

"This is the grim choice for children in western Mosul right now: bombs, crossfire and hunger if they stay – or execution and snipers if they try to run," Save the Children said. Children make up about half the population trapped in the city, the charity said.

The UN's humanitarian coordinator in Iraq, Lise Grande, said in a statement: "We are racing against the clock to prepare emergency sites south of Mosul to receive displaced families."

IS fighters are believed to have developed a network of passageways and tunnels to help them hide and fight among civilians in Mosul. Western Mosul is the site of the old city center with ancient souks, the Grand Mosque and administrative buildings.

jm/bw (Reuters, AFP)