MEXICO CITY, May 29 (Reuters) - The U.S. and Mexico trade negotiators on Friday concluded their first bilateral negotiating round to revise the U.S.-Mexico-Canada Agreement on trade, discussing automotive rules of origin, steel and aluminum trade and economic security, the U.S. Trade Representative's office said.

"The United States concluded discussions with the goals of reducing the trade deficit with Mexico and strengthening American supply chains," USTR said in a statement.

The trade agency said that the two sides will continue to advance their discussions on June 16-17 in Washington, D.C., in talks covering agriculture and "a level playing field." A third round is scheduled for the week of July 20 in Mexico City, but so far the talks exclude USMCA partner Canada.