MEXICO CITY (Reuters) - The United States and Mexico are working through disputes involving American companies in the Mexican energy sector worth more than an estimated $30 billion in investment, the U.S. ambassador to the country said on Wednesday.

       In an interview with Reuters, Ambassador Ken Salazar said his government was making progress in resolving problems affecting U.S. businesses in Mexico, which range from operators of fuel terminals to generators of renewable energy.

       "These 17 companies were companies that had very significant disputes with the Mexican government," Salazar said.

       Mexican President Andres Manuel Lopez Obrador has moved aggressively to redraw energy sector rules for the benefit of state oil company Petroleos Mexicanos (Pemex) and public power utility Comision Federal de Electricidad (CFE), arguing past governments skewed the market in favor of private capital.

       However, that energy policy has put Mexico at odds with the United States and other top trading partners, causing ructions with a string of major corporate investors in the country.

       Some of the projects in dispute are already moving forward, and the "proof will be in the pudding" as to how many of them can be sorted out under the current government, Salazar said.

       (Reporting by Dave Graham and Stephen Eisenhammer; Editing by Marguerita Choy)