Greece is planning to employ translators and print leaflets in Arabic to persuade at least 5,700 migrants crowding waiting areas in Athens' Piraeus port to move to regulated camps, Radio Athina 984 reported Wednesday.
Migrants are currently sleeping in waiting halls normally used by ferry passengers and in more than 1,000 camping tents put up in the docks.
But they say they are reluctant to register in official camps out of fear to get stranded there.
A woman who said that she was in a camp near Larissa, 250 kilometres to the north, told Skai TV in Piraeus that conditions in the regulated facilities were miserable.
Meanwhile, the authorities began planning another camp for 6,300 people on a military compound near the capital in a bid to ease the pressure on Piraeus.
Overall, Greece intends to expand the sheltering capacity by another 30,000 places in the coming weeks, as a so-called readmission mechanism the European Union agreed with Turkey is due to gain momentum.
Under a deal struck by the EU and Ankara this month, any migrants who reach the Greek islands from Turkey as of March 20 who do not apply for asylum or fail to qualify will be returned to Turkey.
In practice, this is to apply to the vast majority of arrivals, up to a maximum of 72,000 people.
With the returns scheduled to begin on Monday, nerves are running raw in the camps, the Athens daily Kathimerini reported Wednesday.
"Kill us here, but don't send us back to Turkey," read a message on a banner waved by migrants in Moria on the island of Lesbos.
Presently, more than 50,000 migrants are stranded in Greece, between Turkey and closed borders to the north. Approximately 4,900 of them have arrived on the Greek islands since March 20, according to Greece's refugee crisis committee.
According to the European Commission, preparations are underway to start returning people under the new deal from Greece to Turkey on Monday.
It will also require changes to Greek and Turkish law, a spokeswoman said, noting that Greece had prepared a draft law on the recognition of Turkey as a safe country to return people to, while Ankara must provide adequate protection for asylum seekers being sent back.
By midday Tuesday, 19 EU member states had pledged an overall 492 police officers and 47 experts to help the bloc's border agency Frontex with the return of people from Greece, the commission spokeswoman said.
The European Asylum Support Office had also received offers from 16 member states to supply 396 experts and 22 interpreters, she added, noting that 170 people had already been nominated and were in the process of being deployed to the region.
In parallel with the return of migrants and asylum seekers to Turkey, the EU is due to start taking in Syrian refugees directly from Turkey on Monday, the spokeswoman said.