Two ferries shipped refugees back to Turkey under a disputed deal intended to stem the human influx into Europe as migrants in a Greek detention camp threw stones in clashes with police on Tuesday.
They were "reacting to their detention conditions and the returns to Turkey," the a police spokesman said. Rights organisations have expressed misgivings about detention conditions on Moria, which holds about 3,000 people.
On Tuesday, 13 people were deported from the island of Lesbos to the Turkish town of Dikili, five were ferried back from Chios to Cesme, and 31 from Kos, police said. Most were Afghans and none had requested asylum in Greece, a government official said.
Just over 340 people have so far been returned to Turkey since April 4 under the accord agreed with the European Union in March after more than 1 million people fleeing war and poverty in the Middle East and beyond reached the continent last year.
The United Nations High Commissioner for Refugees (UNHCR) and human rights groups have expressed serious concerns on the EU-Turkey refugee deal in respect of its content and implementation.
The European Commission said on Tuesday it had been formally reassured by Turkey that it would grant access to asylum procedures to all asylum-seekers sent back from the bloc, a key outstanding element in the deal.
Requests piling up
Under the deal, those arriving in Greece from Turkey after March 20 face being sent back if they do not apply for asylum in Greece or if their application is rejected.
In return, the EU will take in thousands of Syrian refugees directly from Turkey and support Ankara with financial aid, early visa-free travel for its citizens and progress in negotiations to join the bloc.
Turkish Prime Minister Ahmet Davutoglu said on last week that Turkey would no longer need to honour the accord if the EU failed to ease visa requirements by June.
Brussels has said that Turkey fully meets only 19 out of 72 criteria for visa liberalisation. On Tuesday, Turkey's Deputy Prime Minister Mehmet Simsek said Ankara will meet criteria for visa liberalisation by the beginning of May.
In Greece, the government has said authorities would start ruling on asylum applications in late April, but requests have been piling up and it has been criticised for being too slow to process them.
Giorgos Kyritsis, government spokesman for the migration crisis, said Athens was "not cutting corners (and) ... not delaying." About 8,000 refugees and migrants are currently on Greek islands, having arrived after the deal went into effect.
So far under the deal, the International Organisation for Migration (IOM) has facilitated the resettlement of 350 Syrians from Turkey to European countries including in Austria, Denmark, and Germany, it said on Tuesday. It expects to resettle another 300 this week, mostly in France.