The number of migrants and refugees residing at reception centers and camps on the Greek islands has surpassed 20,000 this week for the first time, according to the latest official data.
On Wednesday, the number of people crammed into overcrowded shelters came to 20,050.
The problem is especially acute on Lesvos and Samos in the eastern Aegean.
Lesvos currently hosts 10,943 people, with 8,789 living at the Moria reception center, which is designed to hold 3,100. Conditions are no better on Samos, where a reception center with a capacity of 648 is serving as accommodation for 3,939 people.
At the same time a growing number of migrants and refugees on the islands and the mainland are attempting to fly out of Greece using fake travel documents.
On Tuesday alone, 41 people were arrested at airports on the islands of Samos, Myconos, Santorini, Rhodes and Kos as they tried to board international flights.