Turkish soldiers stand guard as Syrians wait behind the border fences near the southeastern town of Suruc in Sanliurfa province, September 18, 2014. Islamic State fighters besieged a Kurdish city in northern Syria on Thursday after seizing 21 villages in a major assault, prompting a call to arms from Kurds in neighbouring Turkey who urged followers to go and help resist the group's advance. The attack on the city of Ayn al-Arab, known as Kobani in Kurdish, came two days after the top U.S. military officer said the Syrian opposition would probably need the help of the Syrian Kurds to defeat Islamic State. About 3,000 men, women and children arrived at the Turkish border roughly 10 km (6 miles) from Kobani but were still waiting on the Syrian side after night fell, a Reuters witness said, as Turkish forces stopped the crowd from crossing. reuters/Kadir Celikcan

Following clashes between Turkish security forces and Kurdish refugees fleeing the Islamic State group in Syria, Turkey has begun closing some of its border crossings with the war-torn country, according to a BBC report.

Turkish authorities have reportedly closed the border crossing in Kucuk Kendirciler, a small village about a mile from the Kurdish-dominated town of Kobane, with local police saying that they were seeking to prevent Kurdish fighters from going back to Syria to fight the Islamic State group, formerly known as ISIS. The border town of Kobane, as it is known among Kurds, is also known as Ayn al-Arab.

The move comes amid reports of violent clashes on Sunday between demonstrators, who gathered in support of Kurdish refugees, and Turkish authorities. The clashes reportedly took place about three miles from Kobane, with protesters alleging that Turkish authorities were preventing Kurdish refugees from returning to the battlefront in Syria.

The pro-Kurdish Democratic Regions' Party said that two people were injured in the clashes, including one Kurdish legislator who was reportedly hospitalized. The party said that they were protesting the Islamic State group's attacks as well as the border closure, according to media reports.

The Syrian Observatory for Human Rights, meanwhile, reportedly said that ISIS militants had taken control of 64 villages in northern Syria since the fighting began there early Wednesday and that they were closing in on Kobane.

Nearly 100,000 refugees have so far crossed into Turkey from Syria in the past week, according to media reports. More than a million refugees, many of whom are being accommodated in overcrowded schools that have been turned into makeshift shelters, have reportedly fled to Turkey since the 2011 uprising against Bashar Assad.

“Turkey is assisting with all needs but it's huge numbers," Selin Unal, a spokesperson for the United Nations High Commissioner for Refugees, or UNHCR, reportedly said.