EMERGING MARKETS-Brazil's real tumbles on swap move; pesos flat

* Brazil's central bank calls reverse swap auction

* Chile's peso dips 0.1 pct after interest rate held

* Brazil's real down 0.8 pct, Mexico's peso adds 0.1 pct (Adds Brazil's auction results and analyst comments; updates prices)

By Samantha Pearson and Nathalia Ferreira

SAO PAULO, Jan 14 (Reuters) - The Brazilian real sank on Friday after the central bank introduced another aggressive measure to curb its currency, while the Chilean peso dipped following the country's interest rate decision.

Like many emerging economies across Latin America and Asia, Brazil and Chile have struggled with currency appreciation that has made their exports more difficult to sell abroad and flooded the countries with cheap imports.

The Brazilian real was trading 0.77 percent weaker at 1.680 reais per U.S. dollar on the local spot market after the central bank intervened in the futures market for the first time since 2009.

The Chilean peso dipped 0.1 percent to 490.20 per dollar after the country held its benchmark interest rate steady at 3.25 percent, pausing after seven straight increases to help relieve pressure on its currency. For more, see:[ID:nN13283103]

Brazil's central bank called an auction on Friday of reverse currency swaps -- a form of derivative that has the same effect as buying dollars on the futures market. [ID:nN13136301]

It sold all 20,000 contracts on offer, worth $988 million, in its first such auction since May 2009. [ID:nN14137379]

Such strong demand suggests the central bank may return to calling reverse swap auctions on a regular basis as it has done in the past, said Flavio Serrano, senior Brazil economist at Espirito Santo Investment Bank in Sao Paulo.

However, he said the effect on the exchange rate may be limited.

"It is putting some pressure on the currency but it won't really change the long-term trend," he said. "It should continue to move between 1.67 and 1.72."

China's decision to hike banks' reserve requirements, which knocked down the price of many of the region's key commodity exports on Friday, also weighed on the currencies in the early session. But positive U.S. economic data gave support later in the day, helping the Chilean peso to pare most of its sharp early losses. [ID:nLDE70D0SV]

JUGGLING INFLATION AND CURRENCIES

Brazil's latest move could help clear the way for the central bank to raise interest rates by 50 basis points at its meeting next week.

Countries such as Brazil and Chile face a tough dilemma. On one hand, they need to raise interest rates to control rising inflation. But by doing so, they risk worsening their currency problems.

Latin America's relatively high interest rates have attracted a flood of hot money over recent months, pushing the Brazilian real to a 2-year high and the Chilean peso to its strongest in almost 3 years.

Yields on Brazilian interest rate futures contracts <0#DIJ:> rose on Friday as investors bet on a bigger interest rate hike next week.

Elsewhere in the region, Mexico's currency tracked global markets. The peso reversed early losses to firm 0.1 percent to 12.1150 per dollar after surprisingly strong U.S. industrial output in December backed bets that Mexico's closely linked factories will also post stronger-than-expected growth.

Currency intervention in other countries is also making Mexico's free-floating peso more attractive. Local authorities are not expected to introduce similar measures to those in Brazil and Chile because the currency has yet to recover to levels seen before the 2008 financial crisis. (Additional reporting by Michael O'Boyle in Mexico City; Editing by Dan Grebler)