(Adds details on regulations)
MEXICO CITY, Aug 14 (Reuters) - Mexico's Grupo Televisa said on Thursday it paid 8.55 billion pesos ($653.96 million) to acquire the remaining shares in Mexican cable company Cablecom it did not already own.
Televisa, the world's largest provider of Spanish-language content, last year paid 7 billion pesos to buy 51 percent of the company with an option to buy the remaining 49 percent.
Earlier this year, regulator the Federal Telecommunications Institute (IFT) declared Televisa "dominant" in the free-to-air TV market and made it subject to a package of rules to try to increase competition in Mexico.
The company controls more than 60 percent of free-to-air TV.
The new law underpinning that move, which aims to rebalance Mexico's notoriously concentrated telecoms and broadcast markets, came into effect on Wednesday.
The IFT now has 30 days to begin investigating whether Televisa has 'substantial market power' in pay-TV, where it is Mexico's biggest player if its cable and satellite businesses are combined. (1 US dollar = 13.0742 Mexican pesos) (Reporting by David Alire Garcia; Editing by James Dalgleish)