Turkish military forces shelled Kurdish positions on Saturday, hitting the strategic Menagh airbase near the border town of Azaz in Aleppo province. The attack took place only days after the YPG forces reportedly drove the Islamist rebels from the base, with the Russian air force backing the Kurdish assault.

Prime Minister Davutoglu demanded that the YPG militia leave the border region immediately.

"Today retaliation was taken under the rules of engagement against forces that represented a threat in Azaz and the surrounding area," Davutoglu told reporters in televised comments.

Turkey considers the YPG to be an extension of the Kurdistan Workers Party, the force behind the decades-long Kurdish insurgency. The US, however, supports the YPG in the fight against the so-called "Islamic State" group.

"The YPG will immediately withdraw from Azaz and the surrounding area and will not go close to it again," Davutoglu added.

A Kurdish official, however, claimed that the Menagh base had not been captured by the YPG, but by its allies from the Jaysh al-Thuwwar group.

Regime forces reportedly hit

Turkey's state-run Anatolia agency also reported that the Turkish military had targeted Syrian regime forces in Aleppo province, after Syrian troops allegedly fired on a Turkish military guard post.

The incident came as both Turkey and Saudi Arabia mull a ground intervention in Syria, faced with a successful anti-rebel offensive by regime troops.

The US has appealed to all sides to de-escalate cross-border tensions.

"We have urged Syrian Kurdish and other forces affiliated with the YPG not to take advantage of a confused situation by seizing new territory," State Department spokesman John Kirby said in a statement.

"We have also seen reports of artillery fire from the Turkish side of the border and urged Turkey to cease such fires," he added.

Turkey is one of the staunchest opponents of the regime of Syrian President Bashar al-Assad.

Refugees as leverage

The Saturday shelling could raise the stakes as regime forces seem poised to retake the key rebel-held city of Aleppo. Last week, pro-government troops launched a massive offensive with Moscow providing intensive air support.

On Saturday, the pro-government troops continued their march towards Aleppo by capturing the village of Tamoura. In order to completely encircle the rebel-held city, the Syrian government needs to capture at least the following towns: Hayan, Anadan, Hreitan and Kfar Hamra.

The bombardments have sent tens of thousands rushing towards the Turkish border, raising the level of angst in Ankara.

For now Ankara is keeping the new wave of refugees, estimated at 100,000, on the Syrian side of the border in an attempt to pressure Russia to end its air support for the Syrian military.

Helping the 'brothers' in Aleppo

Davutoglu has described the attacks on Aleppo as "barbarity" and warned that hundreds of thousands faced the danger of starvation as the siege intensifies.

"We will help our brothers in Aleppo with all means at our disposal. We will take those in need but we will never allow Aleppo to be emptied through an ethnic massacre," he said.

If the pro-government troops succeed in taking Aleppo, it would be the biggest defeat for the rebels in the five-year-old civil war.

dj/jm (Reuters, AFP)