Giorgos Pantelakos, head of the Thessaloniki immigrant division, said the ring allegedly provided forged identity cards and passports and arranged to put migrants on flights to other EU countries, mostly to Germany.
The ring, believed to have been active since October 2013, charged the mainly Syrian migrants an estimated 3,000-4,000 euros (USD 3,800-5,000) each.
Sixteen such transfers are believed to have taken place, with two or three people put on the flights each time, police said. The ground staff member, who was in charge of the check-in and boarding procedure, allegedly ensured those particular passengers' documents were not closely checked.
More than 17,500 migrants were detained in the country before September 1 this year, with authorities expecting the number to top 31,000 by year's end, compared with 10,500 in 2013.
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Fifty people have died so far this year attempting to get into Greece.
Three of those arrested, including the pilot and the suspected head of the ring, are Cypriot. The suspects also include a Greek travel agent in Thessaloniki and a Pakistani employee of an Athens travel agency, as well as a man who allegedly scouted out potential customers in Athens.
The arrests took place in both Athens and Thessaloniki, with police seizing 39 mobile phones, 56 SIM cards, 25 forged ID cards and five forged passports, as well as 20 computers and 60,000 euros (USD 75,618) in cash among other items.