MEXICO CITY, Nov 12 (Reuters) - Mexican broadcaster Televisa said on Wednesday that a technical glitch at one of its customer service lines was possibly deliberate sabotage by billionaire Carlos Slim's Telmex aimed at stifling competition.

Televisa, Mexico's top broadcaster and pay TV provider, is rolling out services that compete with Slim's phone company.

Televisa executives filed a complaint with Mexico's new telecom regulator, claiming that Telmex had sent calls made to a cable TV service line to the phone of one of Televisa's customers during four hours last Friday.

"It is profoundly worrying that this company tries to present this action as a '(technical) failure,' when in reality it could be an act of commercial sabotage," said Alejandro Bustos, Televisa's vice president for legal affairs.

This month, Televisa launched a new home phone and Internet service in an effort to snap up customers from Slim, whose companies control more than 60 percent of fixed-line service and around 70 percent of the wireless market.

Telmex said in a statement that it "categorically rejects" Televisa's accusations, adding that the complaint looked like a publicity stunt by its rival. It said it had reestablished service in a little more than three hours.

During the last decade, Slim's firms have been repeatedly accused by competitors of providing shoddy service to connect to his network.

Mexican regulators are using new legislation to try to break Slim's stranglehold on the local telecoms market as well as Televisa's control of the broadcast TV airwaves.

The new regulations are spurring a flurry of deals, including last week's $1.7 billion bid by AT&T Inc to acquire Mexico's third-largest wireless operator, Iusacell. Televisa sold its stake in Iusacell in September.

Opposition lawmakers have accused President Enrique Pena Nieto's administration of placing a heavier regulatory burden on Slim than on Televisa. During Pena Nieto's presidential campaign, Televisa's critics accused it of giving him favorable coverage.

Televisa is currently immersed in a political scandal after prominent Mexican journalist Carmen Aristegui on Monday reported that a talent agency linked to the broadcaster gave a house to Pena Nieto's wife, a former soap actress, in 2010.

Televisa said the deal was a common incentive it provided to its actors.

(Reporting by Tomas Sarmiento and Michael O'Boyle; Editing by Cynthia Osterman)