The demand for cheap cigarettes in New York has fueled a large underground market, law enforcement officials say. The growth in cigarette smuggling has been driven by New York City’s $6.46-a-pack tax, the highest in the nation, according to The Wall Street Journal.

The city’s underground cigarette market received attention this week when 10 current and former New York law enforcement officers were arrested for smuggling guns and cigarettes. The defendants in the smuggling scheme made more money on cigarettes than on guns, the article notes.

“Over the past decade we have seen a marked increase in contraband cigarettes coming into the greater New York area,” Joseph Green, a spokesman for the Bureau of Alcohol, Tobacco and Firearms and Explosives’ New York office, told the newspaper.

Black-market cigarettes are generally sold to small shops or are sold in single packs on the street. Some are sold in nightclubs and bars. New York police routinely look for evidence that individual cigarettes are being sold in stores, in an effort to reduce illegal cigarette sales.