MEXICO CITY – Investors welcomed Telmex Internacional onto the Mexican stock market Tuesday, valuing the spinoff of South American assets from telecoms giant Telmex, controlled by tycoon Carlos Slim, at about $16 billion.

Shares of Telmex Internacional, expected to focus on acquisitions in Latin America, jumped 3.9 percent to 8.63 pesos.

Shares of parent company Telmex, retaining its massive but mature Mexico operation, fell 2.2 percent to 12.9 pesos.

Telmex Internacional, which runs cable television operators and Internet service providers in Brazil, Argentina, Chile, Colombia, Ecuador and Peru, is seen as having more growth potential than Telmex.

Creating Telmex Internacional gives investors a choice of plays between a new company that has its eyes on expanding throughout South America and parent Telmex, a slower-moving giant that delivers solid profits and dividends.

As part of the spin-off, Telmex is also holding onto more than its share of the two companies' $10 billion in debt, freeing up Telmex Internacional to buy more companies in South America.

Telmex controls 90 percent of Mexico's fixed-line market and its profits there are healthy. But increasing competition has forced it for the past eight years to freeze prices.

The former government monopoly also faces growing scrutiny from Mexico's antitrust commission.

Telmex posted sales of $4.7 billion in the first quarter, about a third of that coming from assets that are now Telmex Internacional.

While better off than in Mexico, Telmex Internacional still faces tough competition in South America and the success of its spinoff will likely be a far cry from that of America Movil, the mobile phone company Slim split off from Telmex in 2001.

America Movil has become Latin America's largest telecoms, its stock surging 800 percent since its debut.

Brazilian phone company Embratel, Telmex Internacional's largest asset by far, takes about half its revenue from long distance, a business that is languishing as improved Internet technology shrinks profit margins.

(Reporting by Chris Aspin and Noel Randewich; Editing by Brian Moss)