Children are being killed and wounded as well as witnessing horrific violence as Iraqi forces battle the Islamic State group in heavily populated Mosul, Amnesty International said on Thursday.

Iraqi forces launched a massive operation to retake the country's last IS-held city more than two months ago, and have pushed the jihadists out of several neighbourhoods on Mosul's eastern side.

But the battle to retake the city -- where a million or more people may still live -- is far from over, and the heaviest fighting may still be ahead.

"Children caught in the crossfire of the brutal battle for Mosul have seen things that no one, of any age, should ever see," Amnesty's Donatella Rovera said in a statement.

"I met children who have not only sustained horrific wounds but have also seen their relatives and neighbours decapitated in mortar strikes, torn to shreds by car bombs or mine explosions, or crushed under the rubble of their homes," Rovera said.

One woman named Mouna recounted how her daughters, aged eight and 14 months, were killed by mortar fire last month.

"I was telling the girls to go inside. There was shelling and shooting 24 hours a day in our area," the rights group quoted Mouna as saying.

"Just then a mortar landed by the house. I collapsed on the spot, my daughter Teiba fell with her head against the gate, and the little one crawled and crawled till she reached me and collapsed on my lap."

IS overran large areas north and west of Baghdad beginning in June 2014, but Iraqi forces backed by the US-led coalition and Iran have since regained much of the territory they had lost.

But the war against the jihadists has taken a significant toll in money, lives and heavily damaged towns and cities.

Source: AFP