* MSCI LatAm stocks down 0.6%, FX off 0.7%

* Brazil and Chile central bank decisions due Wednesday

* Lula widens lead over Flavio Bolsonaro in Brazil election second-round, poll shows

By Ragini Mathur and Avinash P

June 16 (Reuters) - Latin American stocks and currencies were mixed on Tuesday, after rising in the previous session, as investors weighed an interim U.S.-Iran peace deal and looked ahead to a string of key central bank decisions this week.

The deal would extend a fragile ceasefire announced in April by another 60 days and reopen the Strait of Hormuz.

Still, doubts remained over whether the agreement could bring a lasting solution, with shipping flows and energy exports expected to take weeks to recover, although U.S. President Donald Trump said on Tuesday the text would be made public soon.

"We have not seen a lot of details about the MOU, and there is still a lot of scope for Iran and the U.S. to believe the other party is not standing up to its part of the agreement," said Rachel Ziemba, geopolitical and macro risk analyst and founder of Ziemba Insights.

The U.S. dollar hovered near 10-day lows. The moves were muted before the Federal Reserve's policy decision on Wednesday.

A hawkish Fed signal could lift the dollar and pressure emerging-market currencies.

Brazil and Chile's central banks are also due to announce rate decisions on Wednesday.

MSCI's Latin American stocks index was down 0.6%, while the currencies gauge was down 0.7%. Both indexes were on track to snap a three-day winning run.

Brazil's President Luiz Inacio Lula da Silva extended an advantage over Senator Flavio Bolsonaro in a potential runoff in the October general elections, a CNT/MDA poll showed. The Bovespa stock index fell 0.7%, while the real depreciated 0.8%.

Colombia's stock index was down 1.2%, while the peso gained 1.6%, hitting its strongest levels since December 2020.

Voters in Colombia head to the polls on Sunday to choose between right-wing lawyer Abelardo De La Espriella and leftist senator Ivan Cepeda. Economists, policymakers and investors say the next president will face limited room to advance his economic agenda amid worsening fiscal pressures and a divided Congress.

Elections were also in focus in Peru, where ballots from this month's presidential runoff were still under review. Conservative Keiko Fujimori held a narrow lead over leftist Roberto Sanchez. Peruvian stocks were up 0.6%, while the sol gained 0.7%.

Mexican stocks were 0.3% higher, while the peso was muted. U.S. and Mexican negotiators met in Washington on Tuesday for a second round of talks aimed at revamping the North American trade agreement, as Trump continued to question the future of the 32-year-old free-trade zone with Canada and Mexico.

"USMCA is critical for Mexico, but it is also critical for the United States and U.S. manufacturing," Ziemba said.

"Even if the talks break down, they are likely to resume. But these talks are going to be a driver of volatility in Mexican assets."

Elsewhere, Bloomberg News reported on Monday that the government in Bolivia told investors that foreign-exchange unification and an International Monetary Fund deal were nearing.

Key Latin American stock indexes and currencies at 14:39 GMT:

Stock indexes Latest Daily % change

MSCI Emerging Markets 1776.65 0.72

MSCI LatAm 2997.23 -0.62

Brazil Bovespa 169237.61 -0.69

Mexico IPC 68432.02 0.33

Chile IPSA 10913.92 0.33

Argentina MerVal 3298403.69 -1.62

Colombia COLCAP 2358.62 -1.18

Currencies Latest Daily % change

Brazil real 5.0994 -0.78

Mexico peso 17.215 0.01

Chile peso 887.12 0.29

Colombia peso 3433.7 1.62

Peru sol 3.3773 0.66

Argentina peso 1,432.5 -0.17

(interbank)

Argentina peso 1,445.0 -0.35

(parallel)

(Reporting by Ragini Mathur and Avinash P in Bengaluru; Editing by Andrea Ricci )