Russia denies responsibility after strikes kill at least 33 Turkish troops in Syria NATO to meet at Turkey's request following the incident.

MOSCOW -- Russia has denied it was responsible for airstrikes that killed dozens of Turkish soldiers on Thursday night in the Syrian province of Idlib, in an incident that has threatened to further escalate Syria’s civil war.

NATO on Friday was holding an emergency meeting at Turkey’s request to discuss the situation in Idlib following the incident in which Turkish officials have said at least 33 Turkish soldiers were killed and almost 40 wounded.

The soldiers were in Idlib to support Syrian rebel groups trying to resist a Russian-backed offensive by the Syrian government.

In response to the deaths, Turkey threatened it will now stop preventing Syrian refugees from crossing into Europe, hoping that the prospect of a fresh migrant crisis might prompt Western countries to intervene to stop the Syrian offensive.

A senior Turkish official briefed reporters on Friday that Turkish border guards and coast guard have been ordered to stand down. "We have decided, effective immediately, not to stop Syrian refugees from reaching Europe by land or sea," the official, who requested anonymity, told reporters from Reuters and a number of other international news agencies.

Following the announcement, there were reports of hundreds of Syrian refugees preparing to move toward Turkey’s border with Greece and Bulgaria. Turkish media showed video purportedly of people walking through fields near the border in northwestern Turkey and gathering near the coast.

It was unclear that the numbers of people were higher than usual, but Greece nonetheless announced it was temporarily closing its border crossing with Turkey at Kastanies, near Edirne.

Greece's prime minister Kyriakos Mitsotakis tweeted: "Significant numbers of migrants and refugees have gathered in large groups at the Greek-Turkish land border and have attempted to enter the country illegally. I want to be clear: no illegal entries into Greece will be tolerated. We are increasing our border security.

“Greece does not bear any responsibility for the tragic events in Syria and will not suffer the consequences of decisions taken by others. I have informed the European Union of the situation,” he said in an additional tweet.

The deaths of the Turkish soldiers on Thursday night was the worst loss of life Turkey’s military has suffered since it intervened in Syria in 2016. It was also the most serious incident in the intensifying proxy war between Russia and Turkey in Idlib, where the two countries’ forces are increasingly coming into direct contact.

Intense fighting has been raging for days as Turkey has backed the rebels using artillery and other heavy weaponry, while Russia has conducted airstrikes in support of the Syrian government forces. The strike on Thursday came after the rebels retook the key town of Saraqeb.

Rahmi Dogan, the governor of Hatay province, told the state-run Anadolu news agency that he and other Turkish officials blamed the strikes on the Syrian government.

There had quickly been speculation that the strikes that killed the troops may have been carried out by Russian warplanes. Russia has been conducting the majority of airstrikes in the area in recent days, despite Turkey's statement that the planes had belonged to the Syrian government.

Russia’s defense ministry on Friday denied that its aircraft had been operating in the area and said the Turkish troops had come under fire from Syrian government forces. The ministry in a statement blamed Turkey for failing to inform Russia of the troops’ location and said they had been mixed in with “terrorists.”

The ministry said that Turkey had informed Russia that "no units of the Turkish armed forces were in the area of the village of Behun and they shouldn't have been there."

As soon as Russia became aware of the Turkish casualties it took “exhaustive measures” to have the Syrian government forces ceasefire and allowed Turkey to evacuate its dead and wounded, the ministry said.

The offensive in Idlib has been putting increasingly intense strain on Turkey and Russia’s relations. The strikes occurred on the same day as a meeting between a Russian delegation and Turkish officials in Ankara to discuss the situation in Idlib, which ended inconclusively.

Amid the heightened tensions, two Russian navy frigates, armed with cruise missiles, sailed through Istanbul en-route from the Black Sea to reinforce a task force in the Mediterranean.

Turkey’s president Tayyip Recep Erdogan on Friday spoke with Russia’s president Vladimir Putin by phone about the incident on Friday, both president’s offices said. The two agreed on the need for “additional measures” to resolve the situation in Idlib, the Kremlin said in a readout.

Russia’s foreign minister Sergey Lavrov at a press conference Friday said the Turkish soldiers’ deaths had been “avoidable” but expressed condolences.

Turkey's defense minister Hulusi Akar, disputed that, saying the strikes had continued even though the Turkish troops had informed Russia's military of their location.

“Following the first strike, although another warning was made, the attack continued; during those airstrikes even ambulances were hit,” Akar told the Anadolu news agency in the Turkish border city of Hatay.

In Turkey, Erdogan convened an emergency meeting of his security council in response to his troops’ deaths and on Friday officials vowed retaliation against the Syrian government. Turkish officials later in the day said their military had struck back at 200 Syrian government targets in Syria

"Turkey decided to respond to the illegitimate Assad regime responsible for this attack and the murder of hundreds of thousands of Syrians," spokesman Fahrettin Altun wrote on his Twitter account.

He called on Russia and Iran to “honor their responsibilities” in the Astana process, that designates Idlib a de-escalation zone, and urged the international community to act. "A repeat of past genocides such as those in Rwanda and Bosnia cannot be allowed in Idlib," he wrote.

The NATO meeting summoned by Turkey met on Friday in Brussels. Following it, the alliance’s Secretary General Jens Stoltenberg called on the Syrian government and Russia to halt their offensive and condemned the strikes in Idlib.

“I call on them to stop their offensive, to respect international law, and to back U.N. efforts for a peaceful solution,” Stoltenberg said. “This dangerous situation must be de-escalated,” he added.

But the alliance gave no sign it was moving towards approving any kind of military action or the no fly zone that Turkey has previously called for.

Turkey already hosts 3.6 million Syrian refugees and its government fears that hundreds of thousands more will enter as Bashar al-Assad’s regime advances in Idlib, which is the last rebel-held holdout in Syria. Since December close to a million civilians have already been forced from their homes in Idlib, according to the United Nations.

The U.N. and international aid organisations have been warning of a humanitarian catastrophe in Idlib, which is the last major rebel holdout in Syria and where approximately 3 million civilians are trapped. Huge numbers of people are living in tent camps or in the open, enduring freezing temperatures.

The strikes drew calls in the U.S. from Sen. Lindsey Graham for the international community to intervene and establish a no-fly zone over Idlib. Graham has previously called for a no-fly zone, but there has been little appetite in Washington or European capitals for that.

"The world is sitting on its hands and watching the destruction of Idlib by Assad, Iran, and the Russians," Graham said in a statement. "It is now time for the international community to establish a no-fly zone to save thousands of innocent men, women, and children from a horrible death."

Turkey has frequently threatened before to reopen its borders to allow refugees to Europe, which would reverse a deal it came to with the European Union in 2016 to reduce the numbers.

Migrants and refugees travelling from Turkey have continued to reach Europe. In recent months, as the violence has worsened in Idlib, the numbers arriving in Greece’s Aegean Islands have been the highest since early 2016 at the height of the refugee crisis.