UPDATE 1-Mexico regulator OKs Slim tie-up, Televisa buy plan

* Mexico competition watchdog approves Slim's plan

* America Movil gains on expectations of savings

* Regulator also OKs Televisa proposed buy

By Tomas Sarmiento

MEXICO CITY, Feb 11 (Reuters) - Mexico's competition regulator approved on Thursday tycoon Carlos Slim's plan to consolidate his fixed-line and wireless assets, a major step in creating a Latin American telecommunications behemoth.

Slim launched a $21 billion proposal in January to shift control of his Mexican fixed-line operator Telmex (TELMEXL.MX) TMX.N and regional fixed-line operator Telmex Internacional TELINTL.MX TII.N into his flagship America Movil (AMXL.MX) (AMX.N) cellphone company.

As competition in Latin American telecommunications increases, Slim wants to integrate his companies to create a provider with fixed-line telephone, mobile and Internet services across Latin America to better challenge rivals.

Shares of America Movil gained 1.44 percent to 28.94 pesos ahead of the decision.

Also on Thursday, the regulator approved a proposal by media group Televisa (TLVACPO.MX)(TV.N), which dominates Mexico's television industry and is a growing competitor against Slim's companies, to acquire up to 40 percent of NII Holdings' (NIHD.O) wireless phone operator Nextel Mexico.

Mexican media have reported that Televisa, which has said it wants to expand into cellphone services, taking on America Movil, would look to pay at least $1 billion for a stake in Nextel Mexico.

Regulators have struggled for years to reduce the dominance of Slim's America Movil and Telmex in Mexico's telephone industry, raising questions about whether they will approve the plan or perhaps attach conditions to their blessing. (Reporting by Noel Randewich and Tomas Sarmiento)