Kurds under attack from Turkey in northern Syria say they will no longer prioritise guarding Islamic State detainees if the offensive continues.
The Kurdish-led Syrian Democratic Forces (SDF) currently hold thousands of suspected IS prisoners.
Areas in north-eastern Syria under SDF control have come under heavy bombardment from Turkey since it launched its offensive on Wednesday.
More than 50 civilians have reportedly died on both sides of the border.
Turkey accuses the Kurds of being terrorists and has said it wants to drive them away from a "safe zone" reaching some 30km into Syria.
It also plans to resettle more than three million Syrian refugees in the zone who are currently in Turkey.
According to the United Nations, more than 100,000 people have already been displaced from areas under Kurdish control. The Kurdish administration in north-eastern Syria puts the figure much higher, at more than 191,000.
President Donald Trump's decision to withdraw US troops from the area effectively triggered the Turkish incursion against the SDF - the main Western allies in the fight against IS.
Kurds prioritise their cities and people
Fighting on the Syrian border with Turkey has prevented the SDF from securing IS detention camps in areas under its control, senior official Redur Xelil said in a televised statement on Saturday.
"Guarding IS prisons is no longer a priority. Whoever cares about the secure detention of the prisoners they are welcome to come and find a solution."
Instead, he said, SDF forces would "move to protect our cities and our people".
He warned that the Turkish operation was opening the way for IS to regroup.
"It has revived it and activated its cells in Qamishli and Hassakeh," he said.
IS claims two terrorist attacks in Syria
The comments come after two deadly car bombs in both cities a day earlier, claimed by IS.
Five IS members also escaped from a prison in Qamishli amid Turkish shelling on Friday, the SDF said.
Separately on Saturday, IS declared a new campaign in Syria, which it said was to avenge its members' detention in Kurdish-run prisons.
The SDF said it is currently holding more than 12,000 suspected IS members in seven prisons, and at least 4000 of them are foreign nationals. The exact locations have not been revealed, but some are reportedly close to the Turkish border.
Two camps - Roj and Ain Issa - holding families of suspected IS members are inside the "safe zone".
On Friday the Kurdish-led authorities said discussions were under way on how to move the Ain Issa camp, which had been hit by shelling.
Turkey said it will take responsibility for IS prisoners it finds during its offensive.
Intense fighting near key border town
Clashes on Saturday intensified around Ras al-Ain, amid conflicting accounts over which side was in control of the key border town.
Turkey said its military and allied Syrian rebels had captured the town centre, but the Kurdish-led SDF forces denied it had fallen.
Ras al-Ain and the town of Tal Abyad are two of the key goals in the Turkish offensive.
Elsewhere, Turkey's allies say they have seized strategically important roads 30km away from the border, and captured more than a dozen villages.