
Law enforcement agencies alleged that the gang worked alongside three Russian hackers, who provided them with usernames and passwords stolen using spyware.
It is claimed the Russian hackers shared the password information of thousands of unsuspecting Turkish internet users in exchange for 10 percent of the money stolen.
Hundreds of internet users began to complain about unexpected withdrawals from their online bank accounts in January.
A 20-strong team from the Izmir Organised Crime Bureau investigated the case, discovered the IP addresses of the computers making the illegal transactions, and made simultaneous raids at addresses in Izmir, Fethiye, Didim and Kusadasi.
"In recent years there has been steady growth in the number of viruses and Trojans written to steal banking information from web surfers," said Graham Cluley, senior technology consultant at Sophos.
"Spyware can silently hide on users' computers waiting for them to type in their confidential information and then surreptitiously share it with the hackers."
Cluley applauded the Turkish authorities for looking into the case so speedily, but warned that phishing and spyware is a global problem that requires a global clampdown.
"What's more, all computer users need to defend themselves better against these kind of menaces if they want to continue to bank online safely," he added.
Names of the three suspected Russian hackers have been shared with Interpol.