(In this Sept. 11 story corrects paragraph 2 to provide internet security services instead of provide internet)

The logo of America Movill is seen on the wall at the company's corporate offices in Mexico City, Mexico March 14, 2018. REUTERS/Carlos Jasso

MEXICO CITY (Reuters) - Billionaire Carlos Slim’s America Movil and Mexico’s state oil firm have become embroiled in a public fight over a government contract after the telecommunications giant filed complaints and a legal challenge, saying it unfairly lost the bid.

A rival group, including a unit of Mexican broadcaster Grupo Televisa TLVACPO.MX, won a contract in June for nearly $36 million to provide internet security services to the oil company known as Pemex PEMX.UL.

America Movil AMXL.MX had presented a cheaper offer of roughly $24.5 million, a company spokesman said, and went on to file complaints against Pemex.

A Pemex spokesman said on Monday that the company expects to respond in several days but has not set an exact date.

America Movil, Mexico’s largest internet carrier, and Televisa, the country’s biggest broadcaster, have clashed repeatedly in the Mexican market.

An America Movil spokesman said Scitum, a subsidiary of the company’s Telmex unit, began filing complaints in June to Pemex’s internal auditors and audit committee. The company also filed a legal challenge asking that the contract award be suspended while the case is open.

Telmex subsidiary Triara was also part of the America Movil group vying for the contract.

The turmoil was first reported by Mexico’s Milenio newspaper late last month, making public the type of legal disputes over Mexico government contracts that are frequent but rarely rise to public attention.

Pemex Chief Information Officer Rodrigo Becerra said in an interview that he was content with the tender awarded to Televisa and that Slim’s companies made mistakes in their bid.

He added that when his team joined Pemex in 2016, it found an initial set of bidding requirements that could only have been met by one company, Scitum.

“They had some irregularities. They were, we thought, tilted to one provider in particular,” he said.

An America Movil spokesman denied that the company made mistakes and said that Pemex alone designed its bidding criteria.

Televisa subsidiary Operbes won the internet bid in a consortium with information technology firm TI America. The companies said that technical qualifications outweighed price in winning the Pemex contract.

“On occasion, some competitors present proposals that are apparently more competitive on price but do not meet the technological needs,” the companies said in a statement on Thursday.

America Movil’s Telmex unit as well as Televisa both have substantial government contracting businesses, but neither breaks out those areas in detail.

Mexican think tank IMCO, which studies public contracting, says that Mexican government tenders often lack competition and transparency and are riddled with irregularities.