Islamic State militants has rounded up tens of thousands of people from farms and villages south of Mosul in Iraq to be used as human shields, the United Nations says.
The UN human rights office said on Friday that there were tens of thousands of civilians in the town of Hamam al-Alil, south of Mosul, doubling its population to an estimated 60,000.
The Associated Press reported earlier this week that IS militants had gone door to door in villages south of Mosul, ordering hundreds of people at gunpoint to march north into the city, the largest under their control. Mosul is the focus of a massive Iraqi military offensive launched on 17 October against the extremists.
"They said, 'the army is coming, and they will kill you and rape your women, so you must come with us,'" one of the victims said of the IS militants. He and his family were held in abandoned homes, and were allowed to bring their sheep along for food.
Then, on Thursday, a volley of airstrikes by the US-led coalition pounded the fighters' positions. "They all just fled, ran away and left us," he said.
There was no way to independently confirm the account, but it tracks with those given by other witnesses to the forced displacement who have spoken to the AP in the past week. A US general said thousands have been rounded up, and that the coalition airstrikes are trying to disrupt the militants without harming civilians.
In Hamam al-Alil, the militants separated former members of the security forces from women and children, and took both groups onward to Mosul, the UN said.
The fighters killed 190 former security forces on Wednesday at the Ghazlani military base on the southern edge of Mosul, while 42 civilians were killed at another base for refusing to join IS. Another 24 people were reportedly shot to death on Tuesday, the UN added.
The extremist group has massacred perceived opponents on several occasions since it swept across northern and central Iraq in 2014, often circulating photos and video of the killings and boasting about them online.
As Iraqi forces approach Mosul, the IS extremists are widely believed to be rooting out anyone who could rise up against the militant group, focusing on those with military training or links to security forces.
It is placing "civilian hostages" near strategic locations and fighters, "effectively using tens of thousands of women, men and children as human shields", UN spokeswoman Ravina Shamdasani said in Geneva.
The strategy doesn't seem to have succeeded fully. Those who spoke to the AP after reaching government-held areas said they were able to escape amid the airstrikes.
The coalition used "precision strikes" on vehicles that were unoccupied and far away from civilians to try to disrupt the forced relocations, said US Air Force Brig Gen Matthew C Isler.
"We were able to do that without harming any civilians, and we verified we were able to degrade their planned use of those vehicles," he told the AP. The military later said it had targeted 50 such vehicles, hitting 40-45 of them.
The UN and human rights groups fear that more than 200,000 civilians could be displaced in the opening weeks of the offensive. Mosul, Iraq's second-largest city, is still home to more than 1 million people.
IS has built elaborate defences on the outskirts, including an extensive tunnel network, and has planted large numbers of booby traps to slow the troops' progress. The battle is expected to get even tougher when Iraqi forces enter Mosul.
Troops have retaken 40 villages near Mosul since the operation began, Isler said. But most of the fighting has been in a belt of sparsely populated farming communities outside the city.
Isler said Iraqi troops were consolidating gains made east and south of the city earlier this week, but he insisted that "momentum" was still on their side.
The coalition has stepped up its airstrikes, carrying out three times as many as it did during previous campaigns against other IS-held cities, he added.
Iraqi forces are 6 kilometres from the edge of Mosul on the eastern front, where the elite special forces are leading the charge.
Progress has been slower in the south, where the civilians were rounded up, with Iraqi forces still 35 km from the city.