GEORGETOWN, Dec 10 (Reuters) - Guyana's maritime authority said on Wednesday that supertanker Skipper carrying Venezuelan oil, which was seized by the United States, was falsely flying Guyana's flag.

"The Maritime Administration Department has observed the proliferation and unacceptable trend of the unauthorised use of the Guyana flag by vessels that are not registered in Guyana," it said in a statement.

The authority, which was informed by the U.S. government of the tanker's seizure, plans to take action against the unauthorized use of the country's flag, it added.

(Reporting by Kemol King, writing by Marianna Parraga. Editing by Iñigo Alexander)