A criminal ring using immigrants to produce millions of contraband cigarettes in an underground factory near Thessaloniki has been broken, police said yesterday after arresting a suspected gang member. The 35-year-old ethnic Greek from Armenia is thought to be one of at least 10 members of a ring employing Ukrainian and Moldovan immigrants, in rotating groups of 20, over the past six months in exchange for room and board. He has been charged with forming a criminal organization, money laundering, forgery and customs violations. Raids on the illegal factory and on two nearby warehouses unearthed more than 80 tons of tobacco and 2.3 million packs of contraband cigarettes, most bearing the forged logo of a well-known Greek brand. The factory comprised state-of-the-art manufacturing and packaging machines, underground living quarters for staff and closed-circuit television, police said. Officers described the operation as unprecedented in Greece.