President Recep Tayyip Erdogan ordered the Turkish coastguard to stop migrants from making risky Aegean sea crossings, as fresh clashes erupted Saturday pitting migrants against Greek border police.
Thousands of migrants have massed on the land border with Greece after Erdogan said last week that Turkey would not prevent migrants from leaving for EU territory, sparking violence and an escalating row between Ankara and Brussels.
The Turkish coastguard tweeted on Friday that "on the orders of the president... permission will not be given for migrants to cross the Aegean sea because it is dangerous."
It said, however, Turkey's policy of allowing migrants and refugees to leave was untouched, and the instruction only affected sea crossings.
Over 1,700 migrants landed on Lesbos and four other Aegean islands from Turkey over the past week.
Turkey and the European Union have traded accusations, with Ankara telling Brussels to implement a 2016 migration deal, and the bloc claiming Ankara was using the migrants as political pawns.
Erdogan will head to Belgium where the EU is headquartered for a one-day visit Monday, the Turkish presidency said, but has not given details of his trip.
During a tense hours-long stand-off on Saturday, Greek police used tear gas and water cannons on migrants trying to break fences in the border province of Edirne, according to AFP journalists at the scene.
Meanwhile, Turkish and Greek officials descended into a war of words later on Saturday.
Turkish Interior Minister Suleyman Soylu said Greek Prime Minister Kyriakos Mitsotakis "wouldn't be able to hold the borders" as the weather improves, adding that the Meric (Evros in Greece) river level fell to 40-45cm (16 to 18 inches) in some areas.
Greek government spokesman Stelios Petsas told Open TV that people had been threatened to "board buses to Greece" while others were "beaten to head back to Kastanies."
- 'Open the gates' -
The situation which worsened since Friday saw migrants respond by throwing stones and also shouted "Open the gates" amid clouds of smoke.
Turkish security forces also responded by using tear gas.
An AFP correspondent could see Greek authorities build embankments on its side.
Many migrants have been stranded in biting cold for days at the Pazarkule border, known as Kastanies on the Greek side.
Greek authorities deny using force or acting illegally.
"We have not used any sort of excessive force and we're always reacting, we're never initiating, in terms of responding to the provocations that have taken place on the border," the Greek premier told CNN.
Mitsotakis also accused Ankara of helping people, both at land and at sea, to cross into Greece.
Erdogan's communications director Fahrettin Altun said Turkey "categorically" rejected Mitsotakis' claims.
US Deputy Assistant Secretary Matt Palmer criticised the current border situation as "unsustainable, unacceptable".
Greece's migration minister on Saturday said Athens planned to build two new temporary camps in the northern region of Serres and the greater Athens area to house hundreds of additional asylum seekers after the surge.
- Double standards -
As part of the 2016 agreement, Turkey agreed to stop the flow of migrants to Europe in exchange for billions of euros, but Ankara accused Brussels of failing to fulfil its pledges including taking in refugees from Turkey.
"As a result, Turkey had to divert its resources away from stopping the refugee flow to Europe and instead prepare for a potential influx from Idlib," the last major rebel-held bastion in Syria, Altun said.
The Turkish foreign ministry meanwhile accused the EU of double standards.
"It is unfortunate... that the EU is acting in contradiction with its own principles and values by backing Greece, which is violating international law and human rights," it said.
On Friday, the EU said it rejected Turkey's "use of migratory pressure for political purposes".
Nearly one million people have fled from Idlib in northwestern Syria towards the Turkish border after an escalation in violence by the Russian-backed Syrian regime which killed hundreds of civilians.
But Erdogan and Russian counterpart Vladimir Putin agreed Thursday for a ceasefire in the region.
Turkish Defence Minister Hulusi Akar said Saturday "work had begun" on establishing a security corridor along the key M4 highway in northern Syria, where Turkish and Russian forces will conduct joint patrols on March 15.
He said a Russian delegation would come to Ankara next week for talks, adding there had been no ceasefire violations.