Concerns about US-China trade tensions and anxiety ahead of the US Federal Reserve's interest rate decision kept the mood sober in Latin American markets on Tuesday, with Brazilian shares taking a hit from lender Itau Unibancoa's disappointing earnings.

US President Donald Trump warned China against waiting out his first term to finalize any trade deal, saying the outcome could be no agreement or a worse one if he won a second term.

MSCI's index of Latin American stocks fell more than 0.6%, with Sao Paulo-listed shares shedding half a percent.

Itau Unibanco Holding fell more than 3% as the country's largest lender said it expects its loan book to grow close to the bottom of its target range in 2019 and announced cost cuts amid rising competition.

Other banks such as Banco Bradesco and Banco do Brasil fell more than 1%.

The real edged lower for a second day ahead of a policy decision from Brazil's central bank on Wednesday. A Reuters poll of 27 economists showed the median forecast was for an interest rate cut of 25 basis points to 6.25%.

Brazil is the latest among a series of developing world economies to cut rates to combat a slowdown in growth, spurred by trade disputes. However, the focal point for markets is whether the Fed will signal whether its widely expected 25-basis-point rate cut is the start of a new easing cycle.

"With cross-currents persisting and inflation remaining subdued, we look for the Fed to leave the door open to further easing but to avoid pre-committing to further cuts," TD Securities macro strategist Oscar Munoz said in a note.

Mexico's peso held steady, while its main stock index was weighed down by shares of miner Penoles, which touched their lowest level in more than three years after its Fresnillo subsidiary reported weak earnings.

The Colombian, the Chilean and the Argentine pesos fell between 0.2% and 0.6%.