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EMERGING MARKETS-Latam shares fall, Argentina peso firms on dollar sales plan

(Recasts throughout, updates prices) By Susan Mathew March 14 (Reuters) - Latin American shares fell on Thursday with uncertainty around a trade deal between the United States and China keeping investors on edge, while most regional currencies weakened as caution around Brexit bolstered demand for the dollar.

MSCI's index of Latin American stocks fell for the first time in five sessions, down 0.5 percent, after U.S. Treasury Secretary Steven Mnuchin said a trade summit between the presidents of the U.S. and China would not happen at the end of March.

The summit will be delayed because there is still more work to do in U.S.-China trade negotiations, Mnuchin said. Bloomberg reported that a meeting between the two was more likely to take place in April at the earliest.

The postponement weighs on sentiment as it indicates a resolution to a trade dispute that hit markets around the globe last year is not close, said Luciano Rostagno, chief strategist at Banco Mizuho do Brasil.

Brazil shares fell 0.3 percent, retreating from all-time highs hit last session, with losses capped by gains in energy shares tracking oil prices higher.

The country's economy minister on Wednesday said a watered-down pension reform would threaten future generations. The proposal is currently under review by the Constitution and Justice Commission of the Chamber of Deputies, the first collegiate to review the plan.

But, "despite the difficulties we are facing, we remain confident that the pension reform will be approved later this year and we remain optimistic," said analysts at Gauss Capital in Brazil.

Mexican shares dropped 0.4 percent, while Argentine stocks lost 1.5 percent. Colombian equities however, rose 0.3 percent to their highest in more than four years.

Most Latam currencies slipped as the dollar gained on investors turning cautious about UK Prime Minister Theresa May's chances of getting her Brexit deal approved next week after British lawmakers voted to seek a delay to the March 29 deadline.

Brazil's real ticked down 0.8 percent, while the Mexican peso fell 0.15 percent.

The Argentine peso was an outlier, firming more than 1 percent as the country's treasury said it will sell $9.6 billion in U.S. dollars by the end of 2019 to support the peso.

The announcement of dollar sales along with a higher rate of the central bank's daily sale of liquidity letters supported the peso, said Gustavo Quintana, a trader at local firm PR Corredores de Cambio.

Key Latin American stock indexes and currencies at 2100 GMT: Stock indexes Latest Daily % change MSCI Emerging Markets 1048.20 -0.22 MSCI LatAm 2819.51 -0.45 Brazil Bovespa 98604.67 -0.3 Mexico IPC 41777.81 -0.37 Chile IPSA 5300.79 -0.24 Argentina MerVal 33530.45 -1.45 Colombia IGBC 12836.81 0.29 Currencies Latest Daily % change Brazil real 3.8430 -0.74 Mexico peso 19.3177 -0.20 Chile peso 671.1 -0.36 Colombia peso 3140.5 0.11 Peru sol 3.298 -0.12 Argentina peso 40.7400 1.37 (interbank) (Reporting by Susan Mathew in Bengaluru, José de Castro in Sao Paulo and Jorge Otaola in Buenos Aires; Editing by Chris Reese)