BRASILIA (Reuters) - The Brazilian Air Force is planning to privatize the running of its telecom network used for defense, surveillance and air traffic control, an Air Force spokeswoman said on Tuesday.

The planned public-private partnership is aimed at reducing the cost to the Air Force of modernizing the system and would involve about 4.3 billion reais ($1.3 billion) in investment and operating costs.

Brazilian newspaper O Estado de Sao Paulo reported earlier that 17 companies participated in public hearings on the possible privatization.

U.S. defense contractor and information technology company Harris Corp and Mexico's America Movil, which owns Claro, Brazil's third-largest cellular telephone company, were the most interested, it said.

"We have demonstrated interest in pursuing the program, but are not able to provide any additional input at this time," Jim Burke, Harris Corp's global public relations director, said by email.

Claro representatives declined to comment on the issue.

Estado newspaper, citing an Air Force official in charge of air traffic control, said the private company picked for the project would be expected to invest 1.5 billion reais to modernize and operate the telecom system.

While the network would be privately managed, air traffic control for commercial and military aviation, would continue to be run by the Air Force, Colonel André Jansen told the newspaper.

(Reporting by Anthony Boadle, Ana Mano and Brad Haynes; Editing by Alan Crosby)