Police said on Thursday they had arrested four members of a gang that was holding 65 undocumented migrants against their will in a rural area outside the village of Megali Volvi near Thessaloniki.
Three of the suspects – all foreign nationals – were arrested on Wednesday as they were heading for a remote makeshift shelter in two cars to drop off migrants.
It is understood the suspects had demanded ransom money from the migrants' relatives in exchange for their release.
After a search of the premises, police said they found 65 migrants who were being held without their consent and arrested another man who served as a guard.
Police said they were looking for other gang members.