Ankara (AFP) - Turkey on Friday reopened its border with Syria to Kurds fleeing Islamic State (IS) militants, saying a "worst-case scenario" could drive as many as 100,000 more refugees into the country.
Groups of visibly exhausted Syrian Kurds, most of them women and children who had fled their homes on foot, were shown on live television crossing into the southeastern Turkish village of Dikmetas, under tight security.
"We have taken in 4,000 brothers," Prime Minister Ahmet Davutoglu told reporters during a trip to Azerbaijan. "Their needs will be met. This is a humanitarian mission."
Ankara has given shelter to some 1.5 million refugees from the Syrian conflict under an open-door policy, but since Thursday had refused to accept more for fear of being overwhelmed by a new influx.
That move unleashed a rash of criticism in Turkey, as media reported on desperate Kurds massing on the Syrian side of the border after fleeing escalating clashes between IS and Kurdish fighters.
Earlier on Friday security forces in Dikmetas fired tear gas and water cannon on protesters angry over the refusal to allow in new arrivals.
Deputy Prime Minister Numan Kurtulmus told CNN-Turk that IS jihadists in Syria had advanced to within seven or eight kilometres (4.4 to five miles) of Turkey.
He said 5,000 civilians had crossed into Turkey during the day, adding: "We have worked on a worse-case scenario which would see us subjected to an influx of more than 100,000 refugees".
- Family executed by IS -
A steady stream of refugees, their last remaining possessions in bags balanced on their heads, were seen on live television walking into Turkey.
Some women fainted from exhaustion and hunger. Children seated on their mothers' laps were handed food and water, while an elderly woman in a wheelchair waited behind a line of Turkish soldiers to cross over.
Weeping refugees recounted that IS militants had executed their relatives. Some explained that family members had been left behind to guard over their property.
"God bless the Turkish government. They saved our lives, but what will happen to the rest of us back in Syria?" an elderly refugee told NTV television.
In Dikmetas, the sound of gunfire could still be heard, reports said -- a sharp reminder of the proximity of IS militants across the border.
- Buffer zone strategy -
Turkish President Recep Tayyip Erdogan, whose country is a vocal critic of Bashar al-Assad's Syrian regime, said this week the army was mulling the prospect of setting up a humanitarian buffer zone along the volatile border.
His premier Davutoglu, speaking Friday, said Ankara remained committed to helping Syria's refugee population, but reiterated the strategy of using that buffer zone to extend the help to those on other side of the border.
"We will take in our brothers fleeing to Anatolia from Syria or any other place without any ethnic or sectarian discrimination," he said. "As long as Turkey remains strong, and has a capacity, it will help everyone seeking refuge."
Izzettin Kucuk, the governor of Sanliurfa, described Friday's influx of refugees as an "exceptional" gesture.
"A permission was granted for our strained Syrian brothers to enter Turkey'.... They will be settled after identity and health checks," he said in televised comments.
In recent weeks, Turkey's top civilian and military leaders have held closed-door security summits to discuss the threat from IS jihadists in volatile neighbours Iraq and Syria.
Ankara has also come under Western pressure to control its porous frontier with both countries in order to stop the transit of foreign fighters who would swell IS ranks.
The jihadists have been closing in on a strategic Syrian town near Turkey's border, and expelling Kurdish fighters from surrounding villages.
The capture of Ain Al-Arab -- Syria's third-largest Kurdish town, and known to the Kurds as Kobane -- would give the IS group control of a large strip of Syria's northern border with Turkey.
Kurtulmus, the deputy prime minister, said Turkey knew what to do if IS militants took control directly across its border.
"The Turkish state has the strength to protect itself. It knows very well what to do if IS becomes a neighbour. All measures have been taken," Kurtulmus said, without elaborating.