REFILE-NAFTA negotiators wrap up first round of talks - U.S. official

(Changes dateline to Washington)

WASHINGTON, Aug 20 (Reuters) - Trade negotiators from the United States, Canada and Mexico on Sunday wrapped up the first round of talks to revamp the 23-year-old North American Free Trade Agreement, a U.S. official said. (Reporting by Anthony Esposito; Editing by Nick Zieminski)