New York authorities say they have broken up a transnational criminal ring that trafficked in khat, a plant whose leaves and stems are often chewed for their narcotic effects.

Seventeen suspects were charged in an indictment announced by Attorney General Eric T. Schneiderman and NYPD Commissioner William Bratton on Friday. Nine suspects were from New York City.

The ring distributed khat throughout the city, as well as in Massachusetts and Ohio, authorities said. An England-based defendant was accused of shipping “large quantities of khat” to U.S.-based “managers” in Rochester, N.Y., who would then distribute the plants to customers.

Khat is cultivated in Africa and is most potent when fresh, so it must be shipped efficiently, authorities said. The khat distributed by the suspects was allegedly sourced in Yemen, Kenya and Ethiopia and shipped to the U.S. via multiple countries.

Authorities planned a news conference at 1:30 p.m. to make details of their investigation public.