At least 100,000 people have fled their homes in northeastern Syria following this week's Turkish military incursion in the region, the United Nations (UN) said on Friday.
Meanwhile, Turkish President Recep Tayyip Erdogan said on Friday evening that Turkey "will not stop" its operation in Syria.
"We will never stop this step we have taken against the PYD/YPG... We will not stop it no matter what anyone says," Erdogan said. "We're receiving threats from right and left, saying stop this progress."
U.S. Treasury Secretary Steven Mnuchin said on Friday that President Donald Trump had authorised U.S. officials to draft "very significant" new sanctions to target Turkey after it launched an offensive in northeast Syria, adding that banks were being notified.
In response, Turkey's Foreign Ministry said late on Friday that Turkey would retaliate to any steps against its efforts to fight terrorism.
"Turkey is fighting with terrorist organisations that create a threat to its national security," it said in a statement. "No one should doubt that we will retaliate ... to any step that will be taken against this."
The UN said a growing number of those fleeing their homes in northeastern Syria are taking shelter in schools and other buildings.
"The humanitarian impact is already being felt. An estimated 100,000 people have already left their homes," the UN said in a statement.
"Most are being sheltered in host communities but an increasing number of them are arriving at collective shelters in Al Hassakeh City and Tal Tamer (and) many are seeking refuge in schools."
On Friday, five Islamic State militants broke out of a prison in Qamishli city after Turkish shelling nearby, Marvan Qamishlo, a military media official in the Kurdish-led SDF said.
The Navkur prison is located in a Kurdish area, west of Qamishli city.
A prison officer told the AFP that among the prisoners in the facility were "foreign fighters" of the Islamic State (IS).
Turkey and its Syrian allies have been leading an air and land offensive against the Kurdish forces in northeast Syria since Wednesday (October 9).
Another SDF official mentioned "recurring" bombings near the Jirkine prison, near Navkur, which also holds IS fighters as prisoners.
The Turkish offensive has been condemned by several European countries, which have warned about the fate of IS fighters held in SDF prisons.
Around 12,000 IS fighters, among them Syrians, Iraqis, but also 2,500 to 3,000 foreign citizens from 54 countries, are held in Kurdish prisons, according to Abdel Karim Omar, an SDF official.
Kurdish authorities in the region manage seven high-security prisons, according to Kurdish sources quoted by AFP.
The French Foreign Affairs minister, Jean-Yves Le Drian, said that the fight against Islamic State "risks starting again" and has called for an emergency meeting with the anti-IS coalition, led by the US.