Turkey will no longer allow migrants to cross the Aegean sea to Greece because it is unsafe, the coastguard has said.
The order from President Recep Tayyip Erdogan comes a week after he said he was “opening the doors” for refugees to enter Europe, amid tensions over the Syrian conflict.
The EU accuses him of using migrants for political purposes. It insists its doors are “closed”.
Meanwhile, clashes have again erupted at the land border.
There appears to have been no change in Turkey’s position with regard to letting migrants try to enter Greece via this route.
On Saturday, Greek police fired tear gas at crowds at the border crossing at Kastanies, who responded by throwing stones and shouting “open the gates”, according to the AFP news agency.
The Greek authorities also accused Turkish police of firing tear gas at its police.
What’s the background?
In 2016, a deal was reached whereby Turkey would stop allowing migrants to reach the EU in return for funds from the bloc to help it manage the huge numbers of refugees it hosts.
But since then, tensions between the EU and Turkey have flared on various issues. In recent weeks, a fierce onslaught by Syrian forces and their Russian backers on Idlib, the last province held by Syrian rebels, has led to clashes with Turkey, which supports some rebel groups.
Turkey already hosts some 3.7m Syrians but the conflict in Idlib has led to nearly a million more fleeing to its southern border.
Although the EU promised billions more euros in aid, Turkey was unimpressed and last week decided to open its borders with Greece and even bussed migrants close to the north-western border.
Greece said that the migrants were being “manipulated as pawns” by Turkey in an attempt to exert diplomatic pressure.
It has halted for a month all asylum claims from migrants who enter Greece illegally, and taken aggressive measures to deter them from entering via both land and sea.
In a 24-hour period to Saturday morning, more than 1,200 migrants attempted to cross the land border, most from Afghanistan and Pakistan, an official source told Reuters news agency.
The EU’s foreign policy chief, Josep Borrell, has told refugees to “avoid moving to a closed door”.
The BBC has encountered members of self-styled militias who carry out night-time armed patrols in Greek border towns looking for migrants.
“There are such militia along the entire region,” said Yannis Laskarakis, a newspaper publisher in the city of Alexandroupoli who has received death threats for speaking out against armed vigilantes.
“We have seen them with our own eyes, arresting migrants, treating them badly and if someone dares to help them, he has the same fate.”
What’s the situation in the Aegean?
Greek coastguard boats have been seen forcing migrant vessels back in recent days.
Turkey’s coastguard said it rescued 97 migrants in the sea on Thursday, accusing Greek authorities of having “flattened three boats and left them in a half-sinking state”.
It said on the orders of Mr Erdogan it would stop letting migrants set sail for Greece across the Aegean “because it is dangerous”.
“The approach of not intervening against migrants wishing to leave Turkey remains in practice but this [new] approach covers sea crossings because of the dangers,” the coastguard said.