Erdogan threatens to 'keep doors open' to Europe-bound migrants as clashes erupt on Greece border

Turkey started allowing Syrian refugees to cross to Greece as a means to pressure European governments over the Syrian conflict after Moscow-backed Syrian forces killed 34 Turkish troops there since Thursday.

"What did we do yesterday... We opened the doors," Erdogan said in Istanbul in his first comments after the deaths of Turkish troops in the northwestern Syrian province of Idlib.

"We will not close those doors ...Why? Because the European Union should keep its promises."

Meanwhile, clashes erupted between Greek police and migrants on the border Saturday, after an influx of refugees following deadly strikes in Syria's Idlib province. 

Read more: For Syrians fleeing Idlib, there is nowhere left to run

Greek police fired tear gas at migrants who have amassed at a border crossing in the western Turkish province of Edirne, some of whom responded by hurling stones at the officers

Greece said it has blocked thousands of migrants from crossing its border "illegally" from Turkey.

"Greece yesterday came under an organised, mass, illegal attack of violation of our borders and endured it," government spokesman Stelios Petsas said on Saturday after an emergency meeting with Prime Minister Kyriakos Mitsotakis. 

"We averted more than 4,000 attempts of illegal entrance to our land borders." 

Turkey signed a deal with the EU to stop refugees crossing from its borders after a 2015 migrant crisis. 

The Turkish leader said 18,000 migrants have amassed on the Turkish borders with Europe since Friday, adding that the number could reach as many as 30,000 on Saturday.

Turkey, which is already home to around 3.6 million Syrian refugees, fears more people arriving in the country where there is growing popular discontent against their presence.

"We are not in a situation to handle a new wave of refugees" from Syria, Erdogan said. 

The killing of Turkish troops has increased tensions with Russia, which backs the Syrian regime's relentless offensive to take back the remaining chunks of the Idlib region. Turkey has backed Syrian rebels.

Under a 2018 deal with Russia, NATO-member Turkey has 12 observation posts in Idlib - several of which have been encircled by regime forces. Erdogan has given Damascus until the end of this month to pull back or face the consequences. The deadline is due to expire Saturday night.

Referring to a phone call with Russian President Vladimir Putin on Friday, Erdogan said: "I asked Mr Putin: 'what's your business there? If you establish a base, do so, but get out of our way and leave us face to face with the regime.'"

Erdogan on Saturday confirmed fresh Turkish strikes on regime positions since Friday, including on what officials say was a chemical warfare depot.

"We would not want things to reach this point but as they force us to do this, they will pay a price," Erdogan warned, in an explicit reference to Assad's forces.