"We are on the ground and monitoring the situation closely," IOM spokesman for the Regional Office for the EU, Norway and Switzerland Ryan Schroeder said in answer to a question about whether there have been any problems detected with the return of irregular migrants from Greece to Turkey.
According to Schroeder, IOM warmly welcomes the first arrivals of documented refugees from Turkey to Europe under the Ankara-Brussels deal.
He added that IOM had some concerns about both the legal and the operational aspects of the EU-Turkey deal, especially in how its implementation may affect the most vulnerable migrants.
Under the agreement, Ankara pledged to take back migrants who cross the Aegean Sea to enter the European Union illegally through Greece and send legal Syrian refugees to the bloc in their place.
"We are concerned that this deal risks infringing on the integrity of the asylum and protection system in Greece and Turkey, and we urge countries involved to take all the necessary steps to ensure those safeguards are quickly put in place," Schroeder said.
Frontex reported earlier on Monday that it had assisted Greece in transporting 202 migrants on three ferries from the islands of Lesbos and Chios to Turkey.
In return, the European Union pledged to provide a total of 3 billion euros (over $3.3 billion) to Turkey to help it provide for the refugees there, with a further 3 billion-euro provision possible, as well promising to accelerate Ankara's EU accession bid and introduce a visa-free regime between Turkey and Europe.
The Turkey-EU deal has been criticized by refugee agencies and human rights campaigners questioning whether Turkey can be considered a safe country for refugees.
