EMERGING MARKETS-Latam stocks rise, helped by commodity bets

* Bovespa up 1.34 pct, leads Latin American markets higher

* Chile stocks jump, biggest gain in almost 2 months

* Argentina's MerVal ends at record high (Updates to close, adds comments)

SAO PAULO, Dec 29 (Reuters) - Latin American stocks posted their biggest gain in over a week on Wednesday as investors bet the region's shares would next year be supported by economic recovery, low interest rates and high commodity prices.

The MSCI Latin American stocks index .MILA00000PUS rose 1.3 percent, gaining for a second straight session, and its biggest one-day percentage gain since Dec. 21.

Brazil's benchmark Bovespa index .BVSP climbed 1.34 percent, supported by advances of shares in steelmaker Usiminas, state-run oil giant Petrobras and real estate developers.

Petrobras (PETR4.SA) gained 1.16 percent after the company said its reserves rose by 8.3 billion barrels of oil equivalent after two massive offshore oilfields in the deep-water region known as the subsalt were declared commercially viable. For details, see [ID:nN29276917]

"This week has had very good news flow for the company," said Rafael Dornaus, a stock trader at the Hencorp Commcor brokerage, citing the news about the Lula and Cernambi fields.

Steelmaker Usiminas (USIM5.SA) jumped 2.79 percent after it said late Tuesday it had concluded a deal to sell a 30 percent stake in its Mineracao Usiminas SA mining unit to Japan's Sumitomo Corp for up to $1.93 billion. it will the funds to sharply expand iron ore output.

Brazilian real estate developers PDG Realty (PDGR3.SA) rose 2.41 percent while Rossi Residencial (RSID3.SA) was up 3.05 percent.

Dornaus said Brazilian data showing slower-than-expected inflation in December boosted developers as the report eased concerns the central back could aggressively raise borrowing costs in the months ahead. [ID:nN29270491]

COMMODITY PLAYS SEEN RISING

Analysts said stocks in the region were supported by investors betting the world economy is on the mend and that Latin American economies will post solid growth in 2011.

In Argentina, the benchmark MerVal index .MERV ended at a record high closing level, gaining 0.79 percent to 3,522.60 points, as steelmaker Tenaris (TENA.BA) led gains with a 1.5 percent advance.

Mexico's IPC stock index .MXX rose 0.22 percent on a 3.57 percent gain in shares of miner Penoles (PENOLES.MX).

"Penoles was helped by the expectation that commodities will do well next year. On one hand, demand will rise on the back of an economic recovery and currencies like the dollar are expected to weaken, which boosts the attraction to investments like metals as a refuge," said Carlos Gonzalez, an analyst at brokerage IXE in Mexico City.

"The positive outlook for commodities should also lift stocks across Latin America, given the large amount of companies linked to commodities," he added.

Mexico's IPC is on track to post a nearly 20 percent advance in 2010, while Brazil's main index is set to end the year almost flat. Chile's IPSA has gained around 36 percent.

The IPSA .IPSA jumped 1.09 percent to mark its biggest one-day surge in almost two months.

Data showed Chilean factory output rose less than expected in November, easing pressure on the central bank to raise borrowing costs in order to cool a strong rebound after a devastating earthquake early in 2010. [ID:nN29273433]

Industrial conglomerate Copec CPO.SN added 1.72 percent, chemical maker SQM SQM.SN rose 3.11 percent and steelmaker CAP CAP.SN climbed 1.99 percent. (Reporting by Elzio Barreto and Silvio Cascione in Sao Paulo and Michael O'Boyle in Mexico City)