The Syrian Kurdish YPG militia said on Monday it had seized a major road that brought reinforcements from Islamic State's defacto capital of Raqqa, enabling YPG fighters to lay siege to the militant's stronghold of Tel Abyad.
YPG spokesman Redur Xelil said the militia had surrounded the town along the Turkish border, pushing ahead with an offensive with the help of US-led airstrikes to seize strategic territory held by the jihadists, including their main Tel Abyad-Raqqa supply route.
"Tel Abyad is almost besieged now after the control of the Raqqa-Tel Abyad road," he said.
The Kurdish units were sending reinforcements to the area south of Tel Abyad from both its stronghold in Hasaka province in the northeastern border area and from Kobani, northwest of Tel Abyad.
The Kurdish official said the control of the road will prevent any reinforcements by the militants from Raqqa city further south.
The loss of Tel Abyad would leave the hardline jihadists with only Jarablus border crossing along the Turkish border in their hands.
Tel Abyad has been a main conduit for weapons and smuggling of oil by the militants with Turkey.
Fighting near the border has already forced more than 18,000 people to cross into Turkey from Syria, aid workers say. A further 5,000 are believed to have crossed on Monday, according to a Reuters photographer at the scene.
Soldiers directed the people, many of whom were elderly, women and children, through a passage in a barbed wire fence to a border facility.
A Turkish official and humanitarian worker had said US-led air strikes were partly to blame for the recent displacement of mainly Arabs inhabiting the border area. The US Embassy in Ankara defended its strategy from accusations that it was hurting civilian, saying they were only targeting the militants and their activities.
Turkey is already hosting 1.8 million Syrians, more than any of Syria's other neighbors and one of the biggest refugee populations in a single country anywhere in the world.
The YPG has emerged as the main partner on the ground in Syria for the US-led alliance that has been bombing Islamic State in Syria and Iraq. Its advance into Raqqa province follows a campaign that drove Islamic State from wide areas of neighboring Hasaka province.
Veysel Ayhan, President of International Middle East Peace Research (IMPR), a think-tank which has an office of its humanitarian arm in Akcakale, said YPG along with Syrian opposition forces were very close to taking the town.
The coalition air strikes had prevented Islamic State from sending additional fighters from its Raqqa stronghold, he added.
For the YPG, seizing Tel Abyad would help them link up Kurdish-controlled areas in Hasaka province and Kobani.
The expansion of Kurdish influence in Syria near the border with Turkey is a concern for Ankara, which has long been worried about separatism among its own Kurdish population.
