Thousands of Iraqis are fleeing to Syria in order to escape the fighting around the northern city of Mosul, where a wide-scale offensive is under way to drive out Islamic State, according to an aid group.
Save the Children said that 5,000 people have arrived at the al-Hol camp in north-eastern Syria from the Mosul area in the last 10 days, with 1,000 more waiting to enter at the border.
The group said the camp is ill-equipped to receive the refugees, saying it is "littered with waste and faeces, with a looming risk of outbreaks of disease".
It said there are just 16 toilets shared by more than 9,000 people, many of whom only have access to dirty, untreated water.
Tarik Kadir, head of Save the Children's response to the Mosul crisis, said that "conditions there are among the worst we've seen, and we expect thousands more people to be on their way soon".
Mosul, which fell to IS in 2014, is still home to more than a million civilians.
Meanwhile, a Turkish official said between 100,000 and 400,000 people could flee the fighting in Mosul and make their way towards Syria, Iraq's Kurdish-administrated region or the border with Turkey.
Kerem Kinik, head of the Turkish Red Crescent organisation, said the "humanitarian aspect" of the Mosul operation had not been well thought out by the coalition forces.
He warned that with more than three million people already displaced in Iraq, officials would struggle to cope with the exodus.
Mr Kinik said his organisation was working with officials in northern Iraq and the Iraqi Red Crescent to help support humanitarian efforts there.
Some 20 Turkish aid trucks had been dispatched to the region.
New camps for up to 20,000 families are under construction by international aid agencies in northern Iraq and could be ready within a week.
The Turkish official said he believes the refugees would mostly be "taken under control" within Iraq, but added that Turkey is prepared for a refugee influx.
A refugee camp with some 5,000 tents is being set up by Iraqi and Kurdish authorities east of Mosul.
Project manager Prezzo Mikael said the camp is nearly complete, with running water, electricity and food.
The camp is prepared to receive 5,000 families.
Iraqi authorities have called on people to remain in their homes but are also preparing humanitarian corridors for them to escape the fighting.