Aug. 13 (UPI) -- The U.S. Treasury Department on Wednesday sanctioned four Mexican nationals and 12 companies in Mexico linked to a "brutally violent" cartel involved in a timeshare fraud of resorts in Puerto Vallarta.

The Treasury's Office of Foreign Assets Control said the Jalisco New Generation Cartel is a U.S.-designated Foreign Terrorist Organization "that is increasingly supplementing its drug trafficking proceeds with alternative revenue streams such as timeshare fraud and fuel theft."

Sanctions include blocking all U.S. property owned by the people and the companies named, and the assets must be reported to OFAC. Violations may include civil and criminal penalties.

The agency is reminding current timeshare owners in Mexico: "If an unsolicited purchase or rental offer seems too good to be true, it probably is. Those considering the purchase of a timeshare in Mexico should conduct appropriate due diligence."

The FBI has a timeshare fraud resource page.