The presidents of Turkey and Russia have spoken over the phone to try to defuse tensions that rose significantly in Syria after 33 Turkish troops were killed in an air strike blamed on the Syrian government.

It comes as a new wave of refugees and migrants headed for the Greek land and sea border after Turkey said it would no longer hold them back.

The attack marked the deadliest day for the Turkish military since Ankara first entered the Syrian conflict in 2016 and was also the most serious escalation between Turkish and Russian-backed Syrian forces.

It was not clear whether Syrian or Russia jets carried out the strike, but Turkey blamed Syria’s government and Russia denied responsibility.

Nato envoys held emergency talks at the request of Turkey, a Nato member. Turkey’s 28 allies also expressed their condolences over the deaths and urged de-escalation, but no additional Nato support was offered.

Apart from providing some aerial surveillance over Syria, Nato plays no direct role in the conflict, but its members are deeply divided over Turkey’s actions there, and European allies are concerned about any new wave of refugees.

Turkish President Recep Tayyip Erdogan, whose country already hosts more than 3.5 million Syrian refugees, has long threatened to “open the gates” for millions to flee to Europe unless more international support was provided.

Greece and Bulgaria have increased security at their borders with Turkey in preparation for an influx.

A refugee child cries as he arrives at the village of Skala Sikaminias, on the Greek island of Lesbos
A refugee child cries as he arrives at the village of Skala Sikaminias, on the Greek island of Lesbos (AP/Micheal Varaklas)

The crisis stems from a Syrian government offensive that began on December 1 with Russian military support to retake Idlib province, the last opposition-held stronghold in Syria. Turkey, the main backer of the Syrian opposition, has lost 54 soldiers this month, including the latest fatalities, and now feels the need to respond strongly.

Thursday’s attack sharply raised the risk of direct military confrontation between Turkey and Russia, although Turkish officials blamed Syria for the air strike. The Turkish stock market fell 10%, while the Turkish lira slid against the dollar.

In their phone call, Mr Erdogan and Russian President Vladimir Putin discussed implementing agreements in Idlib, the Kremlin said. Fahrettin Altun, Mr Erdogan’s director of communications, said they had agreed to meet “as soon as possible”.

Two Russian frigates armed with cruise missiles were en route to the Syrian coast, Russian navy officials said. The Admiral Makarov and the Admiral Grigorovich of the Black Sea Fleet both previously took part in Russia’s offensive in Syria.

Nato secretary general Jens Stoltenberg
Nato secretary general Jens Stoltenberg (AP/Olivier Matthys)

Mr Erdogan has made no public comments but spoke with a series of global leaders on Friday.

In a call with Bulgarian prime minister Boyko Borissov, the two agreed to meet on Monday, the Bulgarian government’s press office said. It said the phone call clarified “there is currently no direct threat” to the country bordering Turkey.

Mr Erdogan also talked with German chancellor Angela Merkel and US president Donald Trump, who both called for the Syrian government and its supporters to stop their offensive and for a de-escalation to avoid a humanitarian crisis.

UN Secretary-General Antonio Guterres told reporters that he is talking with Russia and Turkey, appealing for a ceasefire in Idlib, but “we are not yet there”.

The UN Security Council is holding an emergency meeting on Friday.

Russia’s Defense Ministry said the Turkish troops that came under fire were deployed among “terrorist battle formations.” According to coordinates given to Russia’s Reconciliation Centre in Syria, “there were no Turkish military units in the area … and there weren’t supposed to be,” the ministry said.

Russian air forces did not carry out air strikes in the area, its statement said.

Greece Migrants
Hundreds of refugees and migrants in Turkey have begun heading for the country’s land and sea borders with Greece (Giannis Papanikos/AP)

In recent weeks, Turkey has sent thousands of troops as well as tanks and other equipment to Idlib.

As recently as Wednesday, Mr Erdogan gave the Syrian government until the end of February to pull back from its recent advances or face Turkish “intervention”.

The offensive has triggered the largest single wave of displacement in Syria’s nine-year war, sending nearly 950,000 people fleeing to areas near the Turkish border for safety.

Ankara sealed its borders in 2015 and agreed to step up efforts to halt the flow of refugees under a 2016 deal with the European Union.

Turkish Foreign Ministry spokesman Hami Aksoy warned that the movement of migrants to the West could continue if the situation in Idlib deteriorated further.

“Some asylum seekers and migrants in our country, worried about developments, have begun to move towards our western borders,” he said.

“If the situation worsens, this risk will continue to increase.” However, he added that there was “no change” in Turkey’s migration policy.

Greece Migrants
Greek Army officers patrol at the Greek-Turkish border (Giannis Papanikos/AP)

Saying “significant numbers” of migrants and refugees had gathered on the Turkish side of the border with Greece, Greek Prime Minister Kyriakos Mitsotakis tweeted that no illegal crossings would be tolerated and that Greece was not to blame for the “tragic events in Syria”.

He called a meeting of top cabinet and military officials for Saturday.

Greece deployed police and military patrols to the border.

Police said an estimated 1,200 people had gathered late on Friday and periodically tried to push through.

Some managed to cut holes in the fence close to the Kastanies border crossing and attacked police with stones but were driven back with tear gas and stun grenades.