MEXICO CITY, July 7 (Reuters) - U.S. Trade Representative Katherine Tai and Canadian Trade Minister Mary Ng on Wednesday said they raised concerns about Mexican energy and investment policies during an in-person meeting with their Mexican counterpart, Tatiana Clouthier. Tai told reporters during a joint news conference that the United States was closely watching the energy policies of the Mexican government and raising concerns, but did not elaborate. Ng told the news conference she would discuss changes in the Mexican energy sector with the Mexican energy secretary on Thursday. Her office issued a statement saying that Ng had reiterated Canada"s "ongoing concern" with the investment climate in the Mexican energy and mining sectors.