Turkey has deployed additional troops and equipment along part of its border with Syria as fighting north of the city of Aleppo intensifies, security sources said, but Prime Minister Ahmet Davutoglu said there were no immediate plans for any incursion.
Ankara has mooted the creation of a 'secure zone' in Syrian territory due to concerns about Syrian Kurd advances and the presence of Islamic State militants, as well the possibility of a fresh wave of refugees fleeing conflict.
Security sources and officials in the capital Ankara said the Turkish army had stepped up security, also sending in special forces, due to the heavy fighting.
Syrian government forces mounted heavy air strikes on Friday against rebel positions in and around Aleppo, the focus of an insurgent offensive aimed at capturing areas controlled by President Bashar al-Assad.
"It's correct that we have taken precautions to protect our border. If there's any circumstance across the border that threatens Turkish security, orders to act have been given," Davutoglu told broadcaster Kanal 7.
"(But) no one should have the expectation that Turkey will enter Syria tomorrow or in the near term," he said. Some media had speculated an imminent cross-border operation was being planned.
"If anything occurred that were to threaten Turkish security, we wouldn't wait for tomorrow, we would go right in," Davutoglu added.
"But it's wrong to expect that Turkey would undertake such a unilateral intervention in the immediate term if there is no such risk."
A senior Turkish official told Reuters that Ankara was uncomfortable both with the presence of hardline Islamic State militants there and the prospect of Kurdish forces controlling the whole border.
He said Turkey's link to Aleppo was of critical importance and Ankara would act if Kurdish forces took control of Jarablus, a Syrian town just west of the Euphrates river across the border from Turkey's Karkamis.
"Currently many soldiers have been sent to the border region. This shows Turkey's decisiveness. But these are definitely not preparations to cross the border," he said, adding there was no plan to enter Syria unilaterally.
Ankara sees the widening Kurdish presence as a threat, regarding the YPG forces at the border as an offshoot of the PKK militant group which has fought Turkey since 1984 in a conflict which has killed more than 40,000 people.
FEARED WAVE OF MIGRATION
Another Turkish official told Reuters there was also concern about the possibility of a wave of some 1 million more migrants heading for Turkey as a result of clashes in Syria.
"A secure zone is needed on the Syrian side for this reason. We are discussing this with our partners," he said.
U.S. ambassador to Ankara John Bass told reporters on Thursday that Turkey and the United States were working together to address the threat posed by the presence of Islamic State fighters in northern Syria.
But the U.S. State Department said it had no "solid evidence" Turkey was considering a buffer zone in Syria.
Intense fighting, including explosions, could be heard from the Turkish border town of Kilis late on Thursday, about 50 km (30 miles) north of the Syrian city of Azaz, witnesses said. They said the situation was quiet on Friday morning.
The security sources said the Azaz fighting was between Islamic State militants and a joint force of al Qaeda's Syrian offshoot Nusra Front and Western-backed rebels, who have been clashing in the north Aleppo countryside for weeks. The Syrian army and allied militias hold western districts of Aleppo.
Davutoglu said Assad had been cooperating with Islamic State militants in attacking the moderate opposition. Syrian officials have dismissed such allegations in the past, pointing to their own battle against Islamic State.
Davutoglu said if Aleppo were cut off by fighting it could result in a massive new influx of people into Turkey, which is already sheltering more than 1.8 million Syrian refugees.