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 however said Turkey's policy of allowing migrants and refugees to leave was untouched, and the instruction only affected sea crossings. 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.

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.

'Open the gates'

The migrants responded by throwing stones and also shouted "Open the gates". Turkish security forces also responded by using tear gas. Many migrants have been stranded in biting cold for days at the Pazarkule border, known as Kastanies on the Greek side.

The Turkish coastguard said 97 migrants were rescued on Thursday after "the Greek side flattened three boats and left them in a half-sinking state in the middle of the (Aegean) sea". 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," Greek Prime Minister Kyriakos Mitsotakis told CNN.

He 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.

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 the European Union of failing to fulfil its pledges.

Altun listed how the bloc had failed to keep its promises, 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 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 on 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 on Thursday for a ceasefire in the region. Turkish Defence Minister Hulusi Akar said on 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 added a Russian delegation would come to Ankara next week for talks.