Mexico City, May 21 (EFE).- Mexican telecommunications giant America Movil says it has agreed to buy U.S. mobile operator Start Wireless Group for an undisclosed amount. In a filing with the Mexican Stock Exchange, the Mexico City-based company announced its U.S. unit Tracfone Wireless had reached a deal to acquire the assets of Start Wireless Group, an Ohio-based mobile virtual network operator. The transaction is expected to close in the second half of 2013, subject to certain conditions, including regulatory approval, America Movil said.