The Russian owners of Serbia’s only refinery Naftna Industrija Srbije (NIS) have requested an extension of a U.S. license to operate as they negotiate to cede control of the facility to a third party, Serbian Energy Minister Dubravka Dedovic Handanovic said on Tuesday. Gazprom Neft and Gazprom affiliates hold a majority stake in NIS, with the Serbian state owning the remaining 29.9%. The U.S. has waived the sanctions against NIS several times since it sanctioned Russia’s oil industry in January this year. The sanctions on…