Leading Mexican television broadcasters Televisa and TV Azteca are demanding a probe into the partnership between fixed-line phone giant Telmex and satellite TV provider Dish Mexico, saying their dealings are a "disguised merger" being used by multi-billionaire Carlos Slim to enter the domestic television market.

The networks asked the Ifetel regulatory agency to investigate the scope of the contracts signed by Dish, jointly owned by Mexican media conglomerate MVS Comunicaciones and Colorado-based EchoStar Corp., and Telmex.

Those contracts, along with Telmex's option to acquire a stake in Dish, give Telmex effective control over the satellite TV operator, various media outlets have reported.

Televisa called on Ifetel to conduct an "in-depth" investigation into "this simulation that, in practice, constitutes a merger that is illegal and harmful to true competition, and is contrary to the wellbeing of telecommunications users."

Ifetel was created as a part of a 2013 telecommunications overhaul aimed at breaking the hold of dominant players like Televisa and Slim-controlled wireless operator America Movil, Telmex's parent company.

Televisa and Eduardo Ruiz Vega, TV Azteca's director of regulatory compliance, said in separate statements that they have denounced a series of irregularities in the Dish-Telmex agreements for years.

Both broadcasters said a de facto corporation has been created by Telmex and MVS-Dish that has allowed the fixed-line company to offer its broadband customers "triple-play" by unduly packaging phone, Internet and television service.

Dish, however, denied that Telmex has an equity stake, "as public opinion is being artificially led to believe," adding that the Slim-owned company has offered it billing and collection service under contracts signed in November 2008.

Anti-trust regulators reviewed the contracts in May 2009 and found that the dealings between Telmex and Dish did not amount to any type of tie-up, the satellite operator said.

Telmex, for its part, said in a statement that it was not a shareholder in Dish, although it said it could have a direct equity stake in that company in the future if it obtains regulatory approval to provide domestic television service. EFE