Ten Syrian migrants were rescued in Koropi, northeast of Athens, on Sunday after being kept hostage by Pakistani traffickers.
Police said the migrants had paid their captors money to be smuggled from Greece to Italy. Instead, though, they were taken to a house in Koropi, where they were chained up and beaten.
The traffickers demanded that the Syrians contact relatives and convince them to pay between 2,000 and 3,000 euros for each of the migrants being held.
Police were alerted when two of the Syrians were able to break their chains and escape the house.
Officers arrested four Pakistan men on Sunday and were seeking another three.