Greek authorities arrested four Pakistani nationals accused of smuggling migrants and freed eight Syrians held captive in a house near Athens, police said on Sunday.
According to police statement, the four arrested Pakistanis are members of a criminal organisation specialising in snatching and illegally smuggling migrants, who were kept captive and forced to pay money.
Police also freed eight Syrian nationals from the house in Koropi, who were found chained and had been subjected to frequent beatings.
The captives were forced to communicate with relatives who had to make payments to the captors.
Authorities were alerted after two other Syrians managed to escape from the house and seek help.
Greece is the main port of entry into the European Union for migrants and refugees fleeing war-torn or impoverished countries in Africa, Middle East and Indian subcontinent.