A militant Islamist fighter on the streets of Syria's northern Raqqa province (Reuters).
Turkey said Monday that some 130,000 people had flooded across its border from Syria as Kurdish fighters battled Islamic State group jihadists trying to capture a strategic town.
The militant group's spokesman meanwhile issued a statement urging Muslims to kill citizens from countries participating in a US-led anti-jihadist coalition.
IS fighters have been advancing towards Ain al-Arab, Syria's third-largest Kurdish town and known by the Kurds as Kobane, for nearly a week.
But a monitoring group said Monday that Kurdish fighters had ramped up attacks and were holding back the jihadists.
Syrian opposition officials and Kurdish activists have called for international intervention by the US-led coalition assembled to fight IS, but there has been no sign yet of Washington expanding its air campaign in Iraq to Syria.
The IS group has seized large parts of Syria and Iraq, declared an Islamic "caliphate" in areas under its control and committed widespread atrocities including beheadings and crucifixions.
It began advancing toward Ain al-Arab on Tuesday night, prompting a mass exodus to the Turkish border.
Ankara has opened its door to the fleeing Syrian Kurds, with Turkey's Deputy Prime Minister Numan Kurtulmus saying Monday that the number of arrivals was now more than 130,000.
- Terror of fleeing refugees -In Ankara, a Turkish official said three crossings would be open Monday for new arrivals, though earlier an official from the country's emergencies directorate had said only the Mursitpinar crossing would be open.
The arriving refugees, most of them from Syria's Kurdish minority, described their terror as IS militants seized their villages.
"They said in the mosques that they could kill all Kurds between seven and 77 years old," Sahab Basravi told AFP.
"So we collected our things and left, immediately."
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said Monday that IS had seized at least 64 villages and executed at least 16 Kurds.
But director Rami Abdel Rahman said that Kurdish forces backed by Arab Syrians had intensified their attacks against IS fighters, killing 21 jihadists overnight and slowing their advance.
"The progression on the eastern and southern fronts has slowed because of heavy fighting," he told AFP.
"The Kurdish fighters have intensified their attacks since the departure of most of the civilians, and that has obstructed IS from moving further," he told AFP.
IS hopes to seize Ain al-Arab to secure its grip over a long stretch of Syria's northern border with Turkey.
It has battled Kurdish forces in several parts of northern and western Syria, viewing the minority as apostates, even though they are also Sunni Muslims, because of their secular outlook.
Across the border in Turkey, the PKK Kurdish rebel group called on Kurds to cross into Syria to help battle IS.
It urged "mobilisation," a pro-Kurdish news agency reported, saying "the day of glory and honour has arrived."
"We call on our entire people, as well as our friends, to step up the resistance," the PKK statement said.
- Call to kill 'disbelieving' -Turkey, the United States and the European Union consider the PKK a "terrorist" group, though Ankara entered peace talks with the organisation two years ago that have now stalled.
The group has joined forces with Kurdish units fighting IS in both Iraq and now Syria, and the main Syrian Kurdish militia, the People's Protection Units (YPG), is often described as close to the PKK.
Several hundred Kurdish fighters have crossed into Syria to join the fight, but Syria's opposition National Coalition and Kurdish officials have urged Washington and other anti-IS coalition members to intervene, including with air strikes.
Washington has said it would consider strikes against IS in Syria, even without permission from Damascus, but its UN envoy said Sunday "no decisions" had been taken.
Ambassador Samantha Power also predicted that Washington "will not do the air strikes alone if the president decides to do the air strikes".
Some 40 countries have signed up to the US-led coalition against IS, and on Sunday US Secretary of State John Kerry discussed the threat posed by the group in rare high-level talks with his Iranian counterpart in New York.
In a statement posted online on Monday, IS spokesman Abu Mohamed al-Adnani said Muslims should seek out and kill Westerners whose countries have joined the coalition, in particular Americans and the French after their countries carried out strikes in Iraq.
"If you can kill a disbelieving American or European... including the citizens of the countries that entered into a coalition against the Islamic State, then rely upon Allah, and kill him," he said in a statement posted online.