Kurdish forces closed in on a strategic jihadist-held border town in northern Syria on Sunday, AFP reported, prompting an exodus of fearful civilians from surrounding villages.
Backed by allied rebels and air strikes by a US-led coalition, Kurdish militia pressed their offensive on Tal Abyad, used by Islamic State as a gateway from neighboring Turkey.
Late Saturday, the Kurdish People's Protection Units (YPG) advanced to within five kilometers (three miles) of Tal Abyad, the Syrian Observatory for Human Rights said.
The militia also seized at least 20 villages southwest of the border town, the Britain-based monitoring group added.
"They are on the eastern outskirts of Tal Abyad, but the southwestern front is much more difficult because it's more populated," said Observatory director Rami Abdel Rahman.
A Kurdish activist who visits the front line daily said the area's mixed population of Kurds and Arabs was seeking refuge wherever it could.
"Tal Abyad is almost completely surrounded," Arin Shekhmos told AFP.
An AFP correspondent on the Turkish side of the border reported that thousands of would-be refugees were queueing behind the barbed wire seeking asylum.
Another Kurdish activist in the symbolic battleground town of Kobane further west, liberated from ISIS by the Kurds earlier this year, said
authorities there had set up a camp for the displaced.
"We are waiting for the whole border area to be liberated -- from northeastern Syria all the way to Kobane," Mustafa Ebdi told AFP.
Tal Abyad lies on a mostly Sunni Arab part of the border between mainly Kurdish Kobane and Syria's most populous ethnic Kurdish region - Hasakeh province - in the northeast.
Both Ebdi and the Observatory said the Kurds had already occupied the nearby town of Suluk, denying IS access to Tal Abyad from the east.
"IS has completely withdrawn from Suluk. The Kurds are combing through it now and clearing the mines and booby-trapped vehicles there," Abdel Rahman said.
He told AFP that US-led airstrikes had been key in forcing the jihadists to withdraw.