(Corrects first paragraph to say 'formal' demarche, not 'former')

WASHINGTON, Dec 16 (Reuters) - A Chinese Navy warship has seized an underwater drone deployed by an American oceanographic vessel in international waters in the South China Sea, triggering a formal demarche from the United States and a demand for its return, a U.S. defense official told Reuters on Friday.

The incident -- the first of its kind in recent memory -- took place on Dec. 15 northwest of Subic Bay just as the USNS Bowditch, an oceanographic survey ship, was about to retrieve the unmanned, underwater vehicle (UUV), the official said, speaking on condition of anonymity. (Reporting by Phil Stewart; Editing by Chizu Nomiyama)

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