ANKARA — Turkey is facing one of the biggest influxes of refugees from neighboring Syria since the war there began more than three years ago, the United Nations' refugee agency said on Sunday, as civilians continued to flee clashes between Islamic State in Iraq and al-Sham (ISIS) militants and Kurdish forces.

ISIS fighters seized dozens of villages close to the border and advanced on the frontier town of Ayn al-Arab, known as Kobani in Kurdish, as Kurdish commanders issued a rallying cry to Turkish Kurds to join the fight. At least 70,000 people are confirmed to have crossed into Turkey in less than two days, and the real figure may be more than 100,000, Carol Batchelor, UNHCR's representative in Turkey told Reuters on Sunday.

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"I don't think in the last three and a half years we have seen 100,000 cross in two days. So this is a bit of a measure of how this situation is unfolding, and the very deep fear people have about the circumstances inside Syria and for that matter, Iraq," Batchelor said in an interview from the Turkish capital, Ankara. After initially turning people back, Turkish authorities on Friday opened parts of the frontier to allow civilians, mostly women, children and the elderly, to cross to safety.

Turkey is already hosting 1.3 million Syrian refugees and officials estimate the relief effort has cost the government in excess of $3 billion.

ISIS has seized at least 64 villages around Kobani since the onslaught started on Tuesday, using heavy arms and thousands of fighters. It executed at least 11 civilians on Saturday, including at least two boys, The Syrian Observatory for Human Rights said on Sunday.

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RT @aoifeunhcr: "I just want to go home" Another family forced to come to terms with life as refugees pic.twitter.com/ZMeQzbbROm — UN Refugee Agency (@Refugees) September 21, 2014

— Reuters