Police said on Wednesday many of the rescued men were in bad physical condition, having been given minimal food and water. One man required hospitalisation for pneumonia and dehydration.
The migrants 38 Pakistanis, 10 Bangladeshis and two Sri Lankans had been held in a complex of abandoned buildings east of the city of Thessaloniki, where most had been brought six days ago, although some were more recent arrivals.
Authorities were alerted to their plight by relatives who received demands for money for them to be released.
Two Pakistani men were arrested on suspicion of kidnapping and blackmail, among other charges.