* Bovespa climbs back above key support level
* Eletrobras tumbles in worst slide in over 15 years
* Brazil's Bovespa up 1.9 pct, Chile IPSA edges up 0.15 pct (Adds comment, closing prices)
By Danielle Assalve
SAO PAULO, Nov 19 (Reuters) - Brazilian stocks rose on Monday, bouncing back from a more than three-month low after two weeks of steep losses, while shares in the country's Eletrobras electricity firm tumbled the most in more than 15 years.
Brazil's Bovespa index rose 1.89 percent to 56,450.86 as global markets rose following signs of progress in talks to resolve a U.S. fiscal crunch. The index climbed above an important support at 56,200 that eroded last week after the gauge shed more than 5 percent since Nov. 4.
If investors do not enter the market on strong volume and drive a rebound, stocks may be headed back to this year's low, nearly 8 percent down from current levels, chart watchers said.
"It is too early to say if the market could climb consistently higher from here," said Illan Besen, an analyst at brokerage Icap in Rio de Janeiro.
Trading volume in Brazil has been thinner as many traders have been taking a long holiday since last Thursday. The market is closed Tuesday for a holiday.
Global markets were encouraged by comments from U.S. politicians on the chance for a deal to stave off the looming "fiscal cliff," a series of tax and spending changes that will start to come into effect in the new year.
Foreign investors pulled 714 million reais ($345 million) from stocks in Brazil this month, according to data through Nov. 14, the latest from exchange operator BM&FBovespa. Foreigners have pulled out 3.14 billion reais so far this year.
"The market started to price in a chance of failure in the negotiations on the fiscal cliff and the flow of capital to risky assets was drying up," Besen said. "But now we see the possibility of an agreement is being drawn out."
The Bovespa's top commodities producers fueled gains. Oil companies OGX and Petrobras rose 7.47 percent and 0.53 percent, respectively. Iron miner Vale added 1.21 percent.
Shares in state-led electricity holding company Eletrobras shed 15.4 percent, dropping for a second session in a row. The company warned of steeper losses, restructuring and an end to certain dividend payments due to a government plan to cut power rates.
Economists trimmed their forecasts for Brazil's 2013 economic growth for the first time since August, down to 3.96 percent, a weekly central bank survey showed.
Data last week showed weaker retail sales and the first drop in five months in overall activity in Latin America's biggest economy during September as the effect of recent government stimulus measures appeared to flag.
Chile's IPSA index rose 0.15 percent as shares in SQM, the world's top lithium producer, rose 1.76 percent, while retailer Falabella lost 0.68 percent.
Mexico's market was closed for a holiday.
Latin American stock indexes at 2100 GMT:
Stock indexes Latest Daily Year-to
change MSCI Latam 3,542.41 1.15 -2.78
Brazil Bovespa 56,450.86 1.89 -0.53
Mexico IPC 40,830.60 Closed 10.12
Chile IPSA 4,191.12 0.15 0.33
Chile IGPA 20,588.58 0.24 2.28
Argentina MerVal 2,295.33 0.53 -6.79
Colombia IGBC 14,152.88 0.42 11.74
Peru IGRA 20,305.57 1.3 4.27
Venezuela IBC 383,949.38 0.14 228.06
($1 = 2.0770 Brazilian reals) (Additional reporting and writing by Michael O'Boyle in Mexico City; Editing by Dan Grebler)