TWO Russian warships armed with cruise missiles set sail for the Syrian coast today as the EU warned the conflict could slide into "open war".
Turkey demanded backing from Nato allies after Russian bombs killed 33 of its soldiers - but Moscow hit back with a chilling threat that any new advance will "end badly".
Amid mounting tensions today, Russia's defence ministry blamed Turkey for the deaths of its troops in Idlib.
It said the Turkish military had failed to notify Russian counterparts it had soldiers in the area that Syrian forces were shelling.
A spokesman claimed Turkish forces “shouldn’t have been there” according to the information they provided, RIA news agency reports.
The ministry also denied there were any air strikes yesterday, adding it did everything it could to help including making sure Syrian troops stopped artillery fire so Turkey could evacuate its dead and injured.
Some 33 soldiers were killed and 32 hurt on Turkey's worst day since it began its intervention in 2016. The death toll now stands at 54 in February alone.
Turkish rebels retaliated by firing at "every known Syrian target" today and claimed they killed 16 regime soldiers.
President Erdogan has sent thousands of troops and heavy military hardware into Syria to support rebel fighters who are battling the Moscow-backed Assad regime.
He has vowed Turkey will launch a full-scale offensive to repel Syrian forces unless they pull back from Turkish observation posts in the region.
Senior MP Vladimir Dzhabarov, who sits on the Russian parliament's international affairs committee, warned any such full-scale operation in Idlib would "end badly" for Ankara.
It came as the Black Sea fleet sent the frigates Admiral Makarov and Admiral Grigorovich - each armed with Kalibr cruise missiles - to the eastern Mediterranean. A third warship is already there.
Nato chief Jens Stoltenberg called on Russia and Syria to halt "indiscriminate air strikes" and "stop their offensive".
He said after an emergency summit today: "This dangerous situation must be de-escalated and we urge an immediate return to the 2018 ceasefire to avoid the worsening of the horrendous humanitarian situation in the region."
EU foreign policy chief Josep Borrell tweeted: "There is a risk of sliding into a major open international military confrontation.
"It is also causing unbearable humanitarian suffering and putting civilians in danger."
Presidents Erdogan and Putin spoke by phone today and agreed on the need for "additional measures" to normalise the situation, the Kremlin said.
Civilians have also been killed by Assad's forces , prompting fears of a "massacre".
Almost one million civilians have been displaced by the latest fierce battles in northern Syria.
Turkey, which has already taken in 3.6million refugees from the nine-year civil war, says it will not be able to cope with a further influx.
Last night in the wake of the troop deaths, officials said they will no longer stop refugees from trying to reach Europe - overturning a deal with the EU four years ago.
Hours later hundreds of men women and children began marching to the borders with Bulgaria and Greece.
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Both countries said they are beefing up security to repel them.
Erdogan has repeatedly threatened to open the gates to millions of migrants unless European nations gave more support.
But allies are reluctant to be drawn into Syria, and Erdogan has infuriated Nato by buying Russian S-400 air-defence missiles which threaten the F-35 stealth jet.
Families with children were among the Middle Eastern refugees