The Mexican unit of U.S. automaker General Motors said it planned to invest $691 million to expand its operations in Guanajuato, San Luis Potosi and Mexico states.

"GM is about to reach 78 years in Mexico and we celebrate it with this new investment, which means more employment and development opportunities for the regions of Silao, San Luis Potosi and Toluca; and more advanced technology that will benefit our customers," General Motors de Mexico president and managing director Ernesto Hernandez said during a ceremony at the Los Pinos presidential residence.

Some $349 million will be invested in the GM complex in Silao, a city in the central state of Guanajuato, where the new generation of Chevrolet Cheyenne, Silverado and GMC Sierra trucks are being produced.

The second project, which will receive investment totaling $131 million, is the expansion of the plant in San Luis Potosi to produce a new generation of lighter and more technologically advanced transmissions.

The remaining $211 million will go into the expansion of operations at the complex in Toluca, a city in Mexico state, which surrounds the Federal District and forms part of the Mexico City metropolitan area, Hernandez said.

"The Silao and San Luis Potosi investments total $480 million and complete the allocation of the $900 million GM Mexico announced in July 2011. Last July, GM announced the allocation of $420 million for other projects in San Luis Potosi and Silao," the automaker said in a statement.

General Motors has operated in Mexico since 1935.

"The quality of our employees' work continues transcending borders, allowing us to continue attracting investment to maintain a strong production of vehicles, engines and transmissions of outstanding quality for our customers around the world," the GM executive said. EFE