More than 200 people have been put on boats by Greek police and sent back to Turkey under a deal the EU brokered with Ankara to stem the flow of refugees to Europe.
The governor of Turkey's Izmir province, Mustafa Toprak, said that three boats carrying 202 refugees had reached the shores of Dikili, adding that there were no Syrians on board.
But there were conflicting reports on the presence of Syrians with a Greek government spokesman, Giorgos Kyritsis, telling state TV that "all of the migrants returned are from Pakistan, except for two migrants from Syria who returned voluntarily."
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Kyritsis said that 136 people were deported from Lesbos and 66 from the nearby island of Chios.
Later on Monday, 16 Syrian refugees landed in Germany on a flight from Turkey. As part of the deal, for every Syrian refugee returned from Greece to Turkey, another Syrian refugee is to be resettled from Turkey to the EU, with the numbers capped at 72,000.
Under the agreement, all "irregular migrants" arriving in Greece from Turkey since March 20 face being sent back across the Mediterranean.
"What happened on Monday morning was a message from Europe that the door for illegal migration is closed," Al Jazeera's Zeina Khodr, reporting from Lesbos, said.
"They wanted to send this strong message because just yesterday 500 refugees landed on Greece's shore, just a day before the deal was to be implemented."
'Not a safe country'
The deal to send people back across the Aegean Sea has been fiercely criticised by rights groups on ethical grounds.
The AFP news agency on Monday said two Turkish ferries on Lesbos, and another one on Chios, picked up the refugees who were escorted by police from the EU border agency Frontex.
Turkish Interior Minister Efkan Ala had said his country was ready to receive 500 refugees on Monday and Greek authorities had provided 400 names.
READ MORE: The dark side of the refugee deal
The European Union signed the deal with Turkey as it wrestled with the continent's worst refugee crisis since World War II, with more than one million people arriving last year.
About 4,000 refugees have been detained on Greek islands since the agreement came into effect.
"This is the first day of a very difficult time for refugee rights," Giorgos Kosmopoulos, head of Amnesty International in Greece, told the Associated Press news agency from Lesbos.
"Despite the serious legal gaps and lack of adequate protection in Turkey, the EU is forging ahead with a dangerous deal. Turkey is not a safe third country for refugees. The EU and Greek authorities know this and have no excuse."