EMERGING MARKETS-Brazil, Mexico currencies bounce; stocks down

* Latin American stocks mixed in extremely volatile trade

* Mexico peso, Brazilian real supported by central bank actions

* Brazil to sell up to $50 billion in currency swaps

* Mexico sells $1 billion on foreign exchange market to support peso

By Walter Brandimarte

NEW YORK, Oct 23 (Reuters) - Brazil's real and Mexico's peso bounced up on Thursday supported by bold central bank interventions but key stock indexes in Latin America were mixed in very volatile trade.

While a rise in commodity prices brought buoyed shares of raw-material exporters, investors remained concerned about the impact of a global recession in emerging economies.

The Brazilian real BRBY and the Mexican peso MXN=MEX01 reversed early losses after the central banks of both countries heavily intervened to support their currencies.

Mexico's peso was little changed at 13.62 per dollar after the central bank sold $1 billion in the foreign exchange market. Before the intervention, it had lost nearly 14 percent.

The real strengthened 2.8 percent to 2.316 per dollar after the Brazilian central bank unveiled a program to sell up to $50 billion in currency swaps. It also sold dollars on the spot foreign exchange market on Thursday.

"The central bank is trying to show it has the means to support the currency. That puts speculators on alert and shows that, if needed, the central bank will make use of all the weapons it has," said Vanderlei Arruda, currency trader at Souza Barros brokerage in Sao Paulo.

The Chilean peso CLP=CL, on the other hand, weakened 1.4 percent while the Colombian peso was 0.3 percent lower at 2.369 per dollar.

Latin American stock markets were extremely volatile as shares of raw-material exporters tracked commodity prices higher but investors remained fearful of a sharp economic slowdown.

The MSCI equity index for Latin America .MILA00000PUS fell 1.1 percent, with the Brazilian Bovespa index .BVSP down 3.2 percent and the Mexican IPC index .MXX declining 3.4 percent.

On the other hand, Argentina's MerVal .MERV gained 2.0 percent in a technical correction that followed losses of more than 10 percent on Wednesday, when the government scared investors with a plan to take over the country's private pension funds.

Investors fear liquidity in Argentina will further dry up because such funds are among the most active investors in the domestic market.

Emerging-market sovereign bonds remained under pressure, with yield spreads over U.S. Treasuries widening an additional 51 basis points to 853 points, according to the JP Morgan EMBI+ index 11EMJ.

Yields paid on Brazil's global bond due 2040 BRAGLB40=RR jumped to 11.3 percent, its highest level since July 2004, from Wednesday's close of 11.06 percent. On Tuesday, the benchmark Brazilian bond paid yields of 9.2 percent.

Outside of Latin America, other emerging-market governments were also struggling to contain the fallout of the global credit crisis.

Russia's central bank raised its main deposit rate by 0.5 percentage point to fight against capital outflows, while Iceland, Hungary, Ukraine, Serbia, Turkey and Belarus remain in talks with the International Monetary Fund for financial aid.

In another news, Standard & Poor's placed Bulgaria's "BBB+" sovereign credit rating on "CreditWatch negative" on concerns over the country's heightened external vulnerabilities. S&P said it will decide on Bulgaria's ratings by the end of the month, depending on the government response to the crisis. (Additional reporting by Jenifer Correa in Sao Paulo; Editing by Diane Craft)