During the operation, police searches of suspects' houses initially in Thessaloniki, Serres and Halkidiki, where they found large sums of cash, weapons and narcotics.
The suspects were initially remanded for questioning, and arrested afterwards.
Investigations were continuing and more arrests could likely be expected, police said.
According to early information, the ring members targeted mainly Thessaloniki-based nightclub owners, from whom they extorted ‘protection’ money, as well as businessmen and private individuals, forcing the victims to borrow money from them at loanshark rates.
It is estimated that more than 50 people have fallen victim to the ring.
Thessaloniki security police are expected to make announcements on the case on Tuesday.
Police sources said the ring is unrelated to another large extortion and loansharking ring uncovered several months ago, again in Thessaloniki, for similar activities. The 'brains' of the first ring, which numbered 22 members, had 'loaned' 514,000 euros to the local Iraklis soccer club in exchange for the revenues from the team's TV rights.