Most of the 946 people on a ferry that docked at Lavrio, near Athens, had been at a temporary facility hastily built on the island of Lesbos to replace a camp that was burned down by angry residents three weeks ago. Others came from camps on Kos, Samos, Chios and Leros.
The transfer from the Greek islands of people whose asylum bids have been accepted will continue over coming weeks and months, the country's Migration Ministry said Tuesday.
Greek officials have pledged to drastically reduce the islands' migrant populations by moving people who have been granted refugee status to mainland accommodations, taking advantage of a drastic drop in arrivals from Turkey that resulted from stronger policing of the sea border.
The government has also voiced hopes that all the migrants currently on the islands will have been moved to the mainland within six months.
On Tuesday, officials said all unaccompanied teenagers and children living in camps on the islands or on Greece's land border with Turkey had been moved to appropriate facilities on the mainland.
After arriving at Lavrio, the migrants were taken in buses to hotels where they are expected to stay for the next two months.
Nearly 13,000 people have entered Greece illegally so far this year, considerably fewer than in 2019.