(Adds America Movil spokesman's quote, market reaction, background)
MEXICO CITY, July 9 (Reuters) - Mexico's Congress on Wednesday approved laws that implement a landmark telecommunications sector overhaul that aims to curb the power of billionaire Carlos Slim's America Movil and broadcaster Televisa.
The legislation, which fleshes out a constitutional reform pushed through Congress last year, will now head to President Enrique Pena Nieto to be signed into law.
The approval comes a day after America Movil announced it would sell assets in order to avoid tough new regulation aimed at taming companies deemed to have an oversized market share. Shares of the company jumped 4 percent on Wednesday morning, while Televisa shares were down 1.3 percent.
America Movil controls some 70 percent of Mexico's mobile market and 80 percent of the fixed line business, and critics have for years complained of high prices and poor service.
Passage of the so-called "secondary laws" has been delayed by more than six months, complicating the work of a new regulator, the Federal Telecommunications Institute (IFT), that is charged with reducing the power of broadcaster Televisa, which dominates television markets, and America Movil.
Mexico's Senate approved the legislation on Saturday. The Mexican government hailed America Movil's decision, saying it was a direct result of its drive to improve competition.
In a radio interview on Wednesday morning, America Movil spokesman Arturo Elias denied that the company's decision to hive off assets was the first victory of the telecoms overhaul.
"I don't see it that way," he said. "I think it is a change in the telecoms market and we all need to act accordingly."
Televisa, the world's biggest provider of Spanish-language content, has over 60 percent of the free-to-air TV market.
Approving the telecommunications law now paves the way for Congress to pass separate secondary legislation on the government's most ambitious reform, the opening of Mexico's oil and gas industry to private investment after a 75-year state monopoly. (Reporting by Gabriel Stargardter and Alexandra Alper Editing by W Simon)