FILE PHOTO: Flags of the U.S., Canada and Mexico fly next to each other in Detroit, Michigan, U.S. August 29, 2018. REUTERS/Rebecca Cook/File Photo

WASHINGTON (Reuters) - U.S. and Canadian negotiators were “very close” late on Sunday to reaching a deal to update the North American Free Trade Agreement after spending the weekend on last-ditch talks, a U.S. official said, speaking on condition of anonymity.