Several Syrian soldiers were killed in overnight Turkish shelling across the border, the Syrian Observatory for Human Rights watchdog said earlier, without giving an exact figure.

The escalation came after mortar fire from Syria crashed inside the Turkish border town of Akcakale on Wednesday, killing five civilians, including a mother and her three children.

It marked the first time that Turkish citizens had been killed as a result of fire from Syria since the uprising against President Bashar al-Assad’s regime began in March 2011. Turkey has demanded that the UN Security Council take action against Damascus after yesterday’s attack, which drew sharp Western condemnation, with the US calling it ‘depraved.’

Later on Thursday the Turkish parliament was to convene a special session to consider a request from Prime Minister Recep Tayyip Erdogan’s cabinet for approval of possible future cross-border military operations “when deemed necessary.”

Wednesday’s shelling marked the most serious incident between onetime allies Syria and Turkey since June, when Syria shot down a Turkish fighter jet that had briefly strayed into its airspace, killing the two crewmen.

A furious Ankara returned fire, called an emergency meeting of the North Atlantic Treaty Organisation (NATO) and demanded action from the UN Security Council. “Our armed forces in the border region immediately retaliated against this heinous attack… by shelling targets spotted by radar,” Erdogan’s office said in a statement.

“Turkey will never leave unanswered such provocations by the Syrian regime targeting our national security, in line with engagement rules and international law,” his office said. And in a letter to the UN Security Council, Ankara said: “This is an act of aggression by Syria against Turkey. “It constitutes a flagrant violation of international law as well as a breach of international peace and security.

Turkey calls for an immediate end to such unacceptable violations.”  NATO, in an emergency meeting, said that it stood by its member Turkey and “urges the Syrian regime to end flagrant violations of international law.” Syria’s “recent aggressive acts at NATO’s southeastern border” were a “flagrant breach of international law and a clear and present danger” to an ally, it said. —AFP