The first boats carrying migrants being deported from Greece has arrived in Turkey as part of an EU plan aimed at easing mass migration to Europe.
Scores of migrants boarded ferries on the Greek island of Lesbos and arrived in Dikili, western Turkey.
Frontex, the EU’s border agency, told the BBC that 136 people left Lesbos on Monday morning, most from Pakistan.
The EU-Turkey deal has been attacked by rights groups and there are concerns over a lack of preparation.
Another ferry carrying migrants to Turkey is also due to leave the Greek island of Chios on Monday.
Greek authorities said the first people deported did not apply for asylum. There were also citizens from Bangladesh, Sri Lanka and Morocco.
The returns were carried out calmly, despite a small protest at the gate of Lesbos port, the BBC’s Sarah Rainsford at the scene said.
Activists shouted ‘No to deportations’ and ‘EU shame on you’, our correspondent added.
Migrants in Greece have complained of a lack of information about the asylum procedure and some said they were unaware they could be returned.
Frontex has less than one-tenth of the staff needed to do the job, the Associated Press reported.
Under the deal, migrants arriving illegally in Greece are expected to be sent back to Turkey if they do not apply for asylum or if their claim is rejected.
For each Syrian migrant returned to Turkey, the EU is due to take in another Syrian who has made a legitimate request.
Turkey won financial and political concessions as part of the agreement.
Both Turkey and Greece have made a panicked rush to meet this deadline – and neither country is really ready.
Only a fraction of the necessary staff have arrived on the Greek islands to accompany the process and in Turkey the preparation is still sketchy.
Two tents have been erected in Dikili to register the first group from Lesbos, with similar facilities further south to receive migrants sent from Chios.
The Turkish interior minister says non-Syrians will be deported while Syrians will be sent to refugee camps where they will replace those who will be directly resettled in Europe as part of the “one for one” plan.
But there are still grave doubts over whether the deal will hold and if the migrants will be properly treated when they arrive here.
The arrangement has alarmed rights groups, who say Turkey is not a safe country for migrants.
Amnesty International has accused Turkey of illegally returning Syrians to their homeland, something Turkey denies.
Save the Children called the deal “illegal and inhumane”, saying people told them they would kill themselves if sent back to Turkey.
Since the deal was struck in March, about 400 people have been arriving each day on the Greek islands.
Tens of thousands have been stuck in Greece after northern countries closed their borders. There have been clashes in camps amid dire conditions.
One million migrants and refugees have entered the EU by boat from Turkey to Greece since last year.
Many are keen to travel to Germany and other northern EU countries and experts have warned the deal could force them to take alternative, more dangerous routes.
In Austria meanwhile, pro-migrant protesters clashed with police at a border crossing with Italy.
It comes after Austrian Defence Minister Peter Doskozil said soldiers would be deployed at a key transit point, saying the EU’s outer borders were not properly protected.