The first group to depart Athens, comprising 134 Iraqis, was "the biggest voluntary return our country has ever carried out, and the biggest in Europe this year," government spokesman Stelios Petsas told reporters.

Five thousand economic migrants overall will be offered incentives of 2,000 euros ($2,400) per person to return home.

Applicants must have crossed into Greece prior to January 1, 2020, and still be present on the islands of Leros, Samos, Lesbos, Kos and Chios. They will have a month to apply.

The deadline can be extended by another month to make up the required number in the event of a low turnout, the migration ministry has said.

Announced in March, the EU scheme was inactive until now because of the coronavirus pandemic.

The money is designed to help asylum-seekers start afresh in their countries of origin, EU home affairs commissioner Ylva Johansson said at the time.

More than a million migrants and refugees arrived in Greece in 2015 and 2016, according to the UN refugee agency. There are now around 120,000 in the country.

More than 25,000 asylum seekers live in camps on the five Aegean islands that were originally built to handle just 6,095 people.